ARMv7: Add extra barriers for flush_cache_all compressed/head.S

The flush_cache_all function on ARMv7 is implemented as a series of
cache operations by set/way. These are not guaranteed to be ordered with
previous memory accesses, requiring a DMB. This patch also adds barriers
for the TLB operations in compressed/head.S

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>