i965: Move MOCS macros to brw_context.h.

i965: Move MOCS macros to brw_context.h.

These macros are defined in brw_defines.h, which contains a lot of
macros that conflict with autogenerated code from genxml. But we need to
use them (the MOCS macros) in some of that same genxml code.

Moving them to brw_context.h solves that problem and we don't have to
include brw_defines.h.

Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>