ARM: 8015/1: Add cpu_is_pj4 to distinguish PJ4 because it has some differences with V7

The patch add cpu_is_pj4 at arch/arm/include/asm/cputype.h
PJ4 has some differences with V7, for example the coprocessor.
To disinguish this kind of situation. cpu_is_pj4 is needed.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>