build(bl2): enable SP pkg loading for S-EL1 SPMC

Currently the SP package loading mechanism is only enabled when S-EL2
SPMC is selected. Remove this limitation.

Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>
Change-Id: I5bf5a32248e85a26d0345cacff7d539eed824cfc
6 files changed