xlat_table_v2: Fix enable WARMBOOT_ENABLE_DCACHE_EARLY config

xlat_table_v2: Fix enable WARMBOOT_ENABLE_DCACHE_EARLY config

The WARMBOOT_ENABLE_DCACHE_EARLY allows caches to be turned on early during
the boot. But the xlat_change_mem_attributes_ctx() API did not do the required
cache maintenance after the mmap tables are modified if
WARMBOOT_ENABLE_DCACHE_EARLY is enabled. This meant that when the caches are turned
off during power down, the tables in memory are accessed as part of cache
maintenance for power down, and the tables are not correct at this point which
results in a data abort.
This patch removes the optimization within xlat_change_mem_attributes_ctx()
when WARMBOOT_ENABLE_DCACHE_EARLY is enabled.

Signed-off-by: Artsem Artsemenka <artsem.artsemenka@arm.com>
Change-Id: I82de3decba87dd13e9856b5f3620a1c8571c8d87