[MIPS] Eleminate local symbols from the symbol table.

These symbols appear in oprofile output, stacktraces and similar but only
make the output harder to read.  Many identical symbol names such as
"both_aligned" were also being used in multiple source files making it
impossible to see which file actually was meant.  So let's get rid of them.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>