Attempts to address MISRA compliance issues in BL1, BL2, and BL31 code.
Mainly issues like not using boolean expressions in conditionals,
conflicting variable names, ignoring return values without (void), adding
explicit casts, etc.

Change-Id: If1fa18ab621b9c374db73fa6eaa6f6e5e55c146a
Signed-off-by: John Powell <john.powell@arm.com>