arm: cmsis: Convert _Scb*Fault*Reset to use direct CMSIS register access

Coverted:
	_ScbMemFaultMmfarReset
	_ScbBusFaultBfarReset
	_ScbUsageFaultAllFaultsReset

To use direct CMSIS register access.

Also removed scb.h and references as there is no longer any code in it.

Jira: ZEP-1568

Change-Id: I469f6af39d1bd41db712454b0b3e5ab331979033
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>