MIPS: math-emu: Make NaN classifiers static

The `ieee754sp_isnan' and `ieee754dp_isnan' NaN classifiers are now no
longer externally referred, remove their header prototypes and make them
local to the two only respective places still making use of them.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9693/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/math-emu/ieee754dp.c
Simple merge

diff --cc arch/mips/math-emu/ieee754dp.h
Simple merge

diff --cc arch/mips/math-emu/ieee754sp.c
Simple merge

diff --cc arch/mips/math-emu/ieee754sp.h
Simple merge