ARM: kprobes-test: use <asm/opcodes.h> for ARM instruction building

The kprobes test will build certain instructions incorrectly if building
big endian as .word output gets endian-swapped by the linker. Change to
using <asm/opcodes.h> and __inst_arm() to produce instructions.
Acked-by: NJon Medhurst <tixy@linaro.org>
Signed-off-by: NBen Dooks <ben.dooks@codethink.co.uk>
[taras.kondratiuk@linaro.org: fixed unsupported coprocessor instructions]
Signed-off-by: NTaras Kondratiuk <taras.kondratiuk@linaro.org>