ARM: 8055/1: cacheflush: use -st dsb option for ensuring completion

dsb st can be used to ensure completion of pending cache maintenance
operations, so use it for the v7 cache maintenance operations.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --cc arch/arm/include/asm/cacheflush.h
Simple merge

diff --cc arch/arm/mm/cache-v7.S
Simple merge

diff --cc arch/arm/mm/mmu.c
Simple merge