arm: cmsis: Remove nvic.h and use CMSIS NVIC calls directly

Kill of nvic.h and use either CMSIS helper functions for NVIC or direct
NVIC register access via CMSIS for IRQ handling code.

Jira: ZEP-1568

Change-Id: If21910b9293121efe85c3c9076a1c2b475ef91ef
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
5 files changed