ARM: 6355/1: hw-breakpoint: add mechanism for hooking into prefetch aborts

On ARM processors with hardware breakpoint and watchpoint support,
triggering these events results in a debug exception. These manifest
as prefetch and data aborts respectively.

arch/arm/mm/fault.c already provides hook_fault_code for hooking
into data aborts dependent on the DFSR. This patch adds a new function,
hook_ifault_code for hooking into prefetch aborts in the same manner.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: S. Karthikeyan <informkarthik@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>