Invalidate dcache build option for bl2 entry at EL3

Some of the platform (ie. Agilex) make use of CCU IPs which will only be
initialized during bl2_el3_early_platform_setup. Any operation to the
cache beforehand will crash the platform. Hence, this will provide an
option to skip the data cache invalidation upon bl2 entry at EL3

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I2c924ed0589a72d0034714c31be8fe57237d1f06