STM32L1 ADC update for internal channels

[jeromecoutant]

Description

Sampling time was not correct for ADC measurement

target	platform_name	test suite	result	elapsed_time (sec)	copy_method
NUCLEO_L152RE-ARM	NUCLEO_L152RE	tests-api-analogin	OK	14.65	default
NUCLEO_L152RE-ARM	NUCLEO_L152RE	tests-api-analogout	OK	13.5	default
NUCLEO_L152RE-ARM	NUCLEO_L152RE	tests-assumptions-analogin	OK	17.39	default
NUCLEO_L152RE-ARM	NUCLEO_L152RE	tests-assumptions-analogout	OK	13.33	default

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Breaking change

[cmonr]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 3144
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8134/

Triggering tests

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

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2751
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8134/

[mbed-ci]

Test : FAILURE

Build number : 2948
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8134/2948

[0xc0170]

/morph test

[mbed-ci]

Test : FAILURE

Build number : 2956
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8134/2956

[0xc0170]

/morph test

[mbed-ci]

Test : SUCCESS

Build number : 3000
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8134/3000