ARM: 7953/1: mm: ensure TLB invalidation is complete before enabling MMU

commit bae0ca2bc550d1ec6a118fb8f2696f18c4da3d8e upstream.

During __v{6,7}_setup, we invalidate the TLBs since we are about to
enable the MMU on return to head.S. Unfortunately, without a subsequent
dsb instruction, the invalidation is not guaranteed to have completed by
the time we write to the sctlr, potentially exposing us to junk/stale
translations cached in the TLB.

This patch reworks the init functions so that the dsb used to ensure
completion of cache/predictor maintenance is also used to ensure
completion of the TLB invalidation.

Change-Id: Iffb53ea34eb23ce09afe07c842d379ef0cdb638b
Reported-by: Albin Tonnerre <Albin.Tonnerre@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

idea is taken here - https://github.com/CyanogenMod/android_kernel_google_msm/commit/70f0da9da78927c18ddddfc50f53c7ba50044b24