ARM: 7373/1: add support for the generic syscall.h interface

Supplying the asm-generic/syscall.h interface is a
pre-requisite for HAVE_ARCH_TRACEHOOK

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>