MIPS: math-emu: Remove redundant code from NaN comparison

MIPS: math-emu: Remove redundant code from NaN comparison

Remove a redundant call to `ieee754_setandtestcx' in `ieee754sp_cmp' and
`ieee754dp_cmp'.  The IEEE 754 exception requested will have already
been set by a call to `ieee754_setcx' immediately above, because `sig'
has to be non-zero to reach here, and the comparison result returned
will be 0 regardless of the result from the call.  Simplify the return
expression remaining.  All this reducing the size of code by 16 and 12
instructions or 64 and 48 bytes respectively.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9690/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>