[ARM] armv7: add support for asid-tagged VIVT I-cache

ARMv7 can have VIPT, PIPT or ASID-tagged VIVT I-cache. This patch
adds the necessary invalidation of the I-cache when the ASID numbers
are re-used.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>