Build: Minor IAR warnings elimination and fix for 8f17a711

Update the IAR CMSE_FLAG handling for 8f17a711

Fixed a few warnings about unused variables with IAR

Disabled some harmless warnings for IAR

Signed-off-by: TTornblom <thomas.tornblom@iar.com>
Change-Id: I7197ae009e3e85bcb8d8b21b7528108d966ee330