refactor(SMCCC): use a macro to check for the SMCCC version

This is similar to other macros that skip the test if a condition is failed.

Change-Id: If8ff8b29473151edf1872636bce9ee0950851c42
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
4 files changed