arm: v7: Kconfig: Rename CPU_V7 as CPU_V7A

arm: v7: Kconfig: Rename CPU_V7 as CPU_V7A

Currently CPU_V7 kconfig symbol supports only ARMv7A architectures under
armv7 folder. This led to a misconception of creating separate folders
for armv7m and armv7r. There is no reason to create separate folder for
other armv7 based architectures when it can co-exist with few Kconfig
symbols.

As a first step towards a common folder, rename CPU_V7 as CPUV7A. Later
separate Kconfig symbols can be added for CPU_V7R and CPU_V7M and
can co exist in the same folder.

Reviewed-by: Tom Rini <[email protected]>
Tested-by: Michal Simek <[email protected]>
Suggested-by: Alexander Graf <[email protected]>
Signed-off-by: Lokesh Vutla <[email protected]>