Tests: SleepManager: Update test_check() test

Increase delta to 500 us. This value is still short enough to detect
incorrect behavior of the sleep_manager_can_deep_sleep_test_check() fun,
but allows the targets with low LP timer accuracy to pass, i.e.
NUCLEO_F429ZI.

Author: Filip Jagodzinski

TESTS/mbed_hal/sleep_manager/main.cpp

@@ -28,7 +28,7 @@
 #define SLEEP_DURATION_US 100000ULL
 #define SERIAL_FLUSH_TIME_MS 20
 #define DEEP_SLEEP_TEST_CHECK_WAIT_US 2000
-#define DEEP_SLEEP_TEST_CHECK_WAIT_DELTA_US 200
+#define DEEP_SLEEP_TEST_CHECK_WAIT_DELTA_US 500
 
 using utest::v1::Case;
 using utest::v1::Specification;