ARM: Rename arch/arm/cpu/arm_cortexa8 to armv7

The purpose of this patch is to prepare for adding the OMAP4 architecture, which is Cortex A9

Cortex A8 and A9 both belong to the armv7 architecture, hence the name change.

The two architectures are similar enough that substantial code can be shared.

Signed-off-by: Aneesh V <aneesh@ti.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>