ARM: 7421/1: bpf_jit: BPF_S_ANC_ALU_XOR_X support

JIT support for the XOR operation introduced by the commit
ffe06c17.

Signed-off-by: Mircea Gherzan <mgherzan@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>