refactor(cm): factor out EL2 register setting when EL2 is unused

A bunch of registers need to be initialized when EL2 is unused. There
are a lot of them which makes cm_prepare_el3_exit() quite unreadable.
Put them in their own function to improve this.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: If07954ed799643f89f177411d4266bb7c21cd394
1 file changed