[ARM] 4090/2: avoid clash between PXA and SA1111 defines

The Lubbock platform uses both a PXA25x and a SA1111 at the same time.
Both chips have the same "Serial Audio Controller" registers although
the SA1111 one is never expected to be used in preference to the PXA25x
one. So let's disable the SA1111 defines whenever compilation is for a
PXA architecture and make the PXA defines always defined.

This removes a bunch of "already defined" warnings as well since the
current hack to prevent them depended on include ordering which wasn't
always right.

While at it, clean up the SA1111 defines allowing to get rid of the
__CCREG() macro.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>