FDT helper functions: Fix MISRA issues

Moving the FDT helper functions to the common/ directory exposed the file
to MISRA checking, which is mandatory for common code.

Fix the complaints that the test suite reported.

Change-Id: Ica8c8a95218bba5a3fd92a55407de24df58e8476
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
1 file changed