MIPS: Remove compact branch policy Kconfig entries

MIPS: Remove compact branch policy Kconfig entries

Commit ea471f3937ca ("MIPS: Allow compact branch policy to be changed")
added Kconfig entries allowing for the compact branch policy used by the
compiler for MIPSr6 kernels to be specified. This can be useful for
debugging, particularly in systems where compact branches have recently
been introduced.

Unfortunately mainline gcc 5.x supports MIPSr6 but not the
-mcompact-branches compiler flag, leading to MIPSr6 kernels failing to
build with gcc 5.x with errors such as:

  mipsel-linux-gnu-gcc: error: unrecognized command line option '-mcompact-branches=optimal'
  make[2]: *** [kernel/bounds.s] Error 1

Fixing this by hiding the Kconfig entry behind another seems to be more
hassle than it's worth, as MIPSr6 & compact branches have been around
for a while now and if policy does need to be set for debug it can be
done easily enough with KCFLAGS. Therefore remove the compact branch
policy Kconfig entries & their handling in the Makefile.

This reverts commit ea471f3937ca ("MIPS: Allow compact branch policy to
be changed").

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Fixes: ea471f3937ca ("MIPS: Allow compact branch policy to be changed")
Cc: stable <stable@vger.kernel.org> # v4.4+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14241/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>