Added to option --auto handler for -f <mcu> filter switch.

[PrzemekWirkus]

Description

Now using -f switch will filter target platforms to test when you use for example auto-detection (--auto option). Use comma to pass more MCU names to -f filter.
You can't apply regular expression on names, only give full platform name!

For system connected with two boards: NUCLEO_L053R8 and KL25Z we can check configuration (using switch --config):
We can see both boards are detected and we will test both of them if test suite will be executed without -O or --config option.

$ singletest.py --auto --config
MBEDLS: Detecting connected mbed-enabled devices...
MBEDLS: Detected NUCLEO_L053R8, port: COM35, mounted: E:
MBEDLS: Detected KL25Z, port: COM89, mounted: F:
MUTs configuration in auto-detected:
+-------+-------------+---------------+------+-------+
| index | peripherals | mcu           | disk | port  |
+-------+-------------+---------------+------+-------+
| 1     |             | NUCLEO_L053R8 | E:   | COM35 |
| 2     |             | KL25Z         | F:   | COM89 |
+-------+-------------+---------------+------+-------+

Test specification in auto-detected:
+---------------+-----+------+
| mcu           | ARM | uARM |
+---------------+-----+------+
| KL25Z         | Yes | -    |
| NUCLEO_L053R8 | -   | Yes  |
+---------------+-----+------+

Building original configuration (no filter):

$ singletest.py --auto -j 8 -O
MBEDLS: Detecting connected mbed-enabled devices...
MBEDLS: Detected NUCLEO_L053R8, port: COM35, mounted: E:
MBEDLS: Detected KL25Z, port: COM89, mounted: F:
Building library CMSIS (KL25Z, ARM)
Building library MBED (KL25Z, ARM)
Building project DETECT (KL25Z, ARM)
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Building library CMSIS (NUCLEO_L053R8, uARM)
Building library MBED (NUCLEO_L053R8, uARM)
Building project DETECT (NUCLEO_L053R8, uARM)
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Completed in 3.68 sec

Filtering out other boards and checking configuration, leaving KL25Z:

$ singletest.py --auto -j 8 -O -f KL25Z --config
MBEDLS: Detecting connected mbed-enabled devices...
MBEDLS: Detected NUCLEO_L053R8, port: COM35, mounted: E:
MBEDLS: Detected KL25Z, port: COM89, mounted: F:
MUTs configuration in auto-detected:
+-------+-------------+-------+------+-------+
| index | peripherals | mcu   | disk | port  |
+-------+-------------+-------+------+-------+
| 2     |             | KL25Z | F:   | COM89 |
+-------+-------------+-------+------+-------+

Test specification in auto-detected:
+-------+-----+
| mcu   | ARM |
+-------+-----+
| KL25Z | Yes |
+-------+-----+

Building original configuration (with applied filter):

$ singletest.py --auto -j 8 -O -f KL25Z
MBEDLS: Detecting connected mbed-enabled devices...
MBEDLS: Detected NUCLEO_L053R8, port: COM35, mounted: E:
MBEDLS: Detected KL25Z, port: COM89, mounted: F:
Building library CMSIS (KL25Z, ARM)
Building library MBED (KL25Z, ARM)
Building project DETECT (KL25Z, ARM)
.
.
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Completed in 1.33 sec