Patch from Catalin Marinas

Recent patches introduced the write_can_lock() call in the kernel/ptrace.c
file. Implement the __raw_* variants on ARM (SMP) as well.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>