timer: Fixes a build error when MVIC is used

MVIC does not have _REG_TIMER_CFG defined because it does
not have a timer config register. Add checks for MVIC at
places where it is used.

Jira: ZEP-1015
Change-Id: I59f5c43cc2d1b17cf9e88b940631c2542e9729ab
Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>
1 file changed