Fix bug in Nordic SDK 14.2 I2C driver

[marcuschangarm]

Interrupts were not enabled before transmitting data leading to
missed interrupts.

Description

Pull request type

[x] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

[0xc0170]

As I can see some other bug fixes in their driver, do we keep a list of what we are changing , so can be sent upstream for review (or kept as a log for us what has changed in the driver).
We do not usually touch SDK.

Changes look good to me

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 1855
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6721/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1499
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6721/

[mbed-ci]

Test : SUCCESS

Build number : 1663
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6721/1663