clk: socfpga: use ARCH_INTEL_SOCFPGA also for 32-bit ARM SoCs (and compile test)

ARCH_SOCFPGA is being renamed to ARCH_INTEL_SOCFPGA so adjust the
32-bit ARM drivers to rely on new symbol.

There is little point to share clock controller drivers between 32-bit
and 64-bit platforms because there will not be a generic image for both
of them.  Therefore add a new Kconfig entry for building 32-bit clock
driverss, similar to one for 64-bit.  This allows enabling compile
testing.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>