bluetooth: hci-driver: Remove temporary defines

SDC_USE_NEW_SDC_SUPPORT_API:
The sdc_support_* API that returns void is now in use in nrfxlib.
So there is no need to support the old API.

SDC_USE_NEW_MEM_API:
This was added in d53b155 and should
have been removed a long time ago.

Signed-off-by: Vegard Gulaker <[email protected]>

Author: vegardgu