bus/arm-cci: add dependency on OF && CPU_V7

The arm-cci code uses device tree helpers for initialization
that don't work on kernels built without CONFIG_OF. Further,
it contains an inline assembly in cci_enable_port_for_self()
that uses ARMv7 instructions and fails to build when targetting
other ARM instruction set versions.

This works around both issues by limiting the scope of the
Kconfig symbol to platforms that can actually build this driver
cleanly.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Shawn Guo <shawn.guo@linaro.org>