MIPS: Remove unreachable break statements from cp1emu.c

There were many cases of:

   return something;
   break;

All those break statements are unreachable and thus redundant.

Signed-off-by: David Daney <david.daney@cavium.com>
Reviewed-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5727/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>