Platform: Update default NV counter implementation

Change the BL2 counters to use the OTP HAL (Other counters remain using
a flash implementation).

Use the OTP flash implementation backend code to provide resistance to
asynchronous power loss. Remove other implementations from platforms
which were solving this issue.

Change-Id: I60d188370c184e531ed15693f432035928ae7571
Signed-off-by: Raef Coles <raef.coles@arm.com>
14 files changed