fix(gic): wrap cache enabled assert under plat_can_cmo

with reference to feature 04c730 (feat(cpus): make cache ops conditional),
booting with caches in debug recovery means SCTLR_C_BIT will be 0.
Wrap the assert for the d-cache enabled check in CONDITIONAL_CMO and
plat_can_cmo calls to allow booting with d-cache disabled.

Signed-off-by: Channagoud kadabi <kadabi@google.com>
Change-Id: I80153df493d1ec9e5e354c7c2e6a14322d22c446