ARM: 6166/1: Proper prefetch abort handling on pre-ARMv6

Instruction faults on pre-ARMv6 CPUs are interpreted as
a 'translation fault', but do_translation_fault doesn't
handle well if user mode trying to run instruction above
TASK_SIZE, and result in the infinite retry of that
instruction.

CC: <stable@kernel.org>
Signed-off-by: Anfei Zhou <anfei.zhou@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>