NRF5x: Fix config of LFCLK source / settings.

[andrewleech]

Description

The NRF5x targets all have config entries to set the low frequency clock source and a couple of settings for the RC source.
https://github.com/ARMmbed/mbed-os/blob/6634e4606d49c298be896cdf3c8aa9942067c5a2/targets/TARGET_NORDIC/TARGET_NRF5x/LF_Clock_config.md
https://github.com/ARMmbed/mbed-os/blob/master/targets/targets.json#L3744

The defines these map through to no longer exist in SDK14 / TARGET_NRF5x however:
https://github.com/ARMmbed/mbed-os/blob/2104d8ab5b6be5ce382b3b0e74085e1c2c677f85/features/FEATURE_BLE/targets/TARGET_NORDIC/TARGET_NRF52/source/btle/btle_clock.h

Nordic changed their defines for these things to NRF_SDH_CLOCK_LF_SRC, NRF_SDH_CLOCK_LF_RC_CTIV & NRF_SDH_CLOCK_LF_RC_TEMP_CTIV which are currently hardcoded in each softdevice mbed_lib.json

These settings are required if you want to run a nrf5x system without the external 32K crystal.

This PR maps these existing config entries through to the new defines used in nordic code.

### Pull request type

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

[0xc0170]

Why is this error now? The text indicates that default config would be used (should not be an error?)

[andrewleech]

Oops, that was changed for debugging only, didn't mean to commit it. I'll fix in the morning.

[cmonr]

@marcuschangarm Mind taking a look?

@andrewleech A reminder that this is still awaiting an update.

[andrewleech]

Oh, yeah. I thought I did push that update, clearly not.

[cmonr]

@andrewleech Was there suppose to be an update commit attached to your last comment?

[andrewleech]

It's pushed now

[cmonr]

/morph build

[mbed-ci]

Build : FAILURE

Build number : 2787
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7652/

[andrewleech]

Drats, I'll look into the build fails next week as well then

[andrewleech]

Ok that previous build failure should be fixed. I'd stripped out some old defines I erroneously thought were no longer used.

[cmonr]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 2860
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7652/

Triggering tests

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

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2490
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7652/

[mbed-ci]

Test : SUCCESS

Build number : 2622
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7652/2622

[0xc0170]

/morph mbed2-build