[MIPS] tx4927: Cleanup unused macros and non-standard IO accessors.

This patch removes many unused constants, replaces non-standard IO
accessors with standard ones, and kills terrible tx4927_mips.h file.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
8 files changed