[MIPS] Remove commented out code to add -mmad for Nevada.

    
Adding -mmad is not usable since over half a decade in gcc and when
fixed the proper -march option values should enable the use of the
mad, madu and mul instructions of the R5500, RM5200, RM7000 and RM9000
families.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -233,7 +233,6 @@ CHECKFLAGS-$(CONFIG_CPU_R5432)	+= -D_MIPS_ISA=_MIPS_ISA_MIPS4
 cflags-$(CONFIG_CPU_NEVADA)	+= \
 			$(call set_gccflags,rm5200,mips4,r5000,mips4,mips2) \
 			-Wa,--trap
-#			$(call cc-option,-mmad)
 CHECKFLAGS-$(CONFIG_CPU_NEVADA)	+= -D_MIPS_ISA=_MIPS_ISA_MIPS4
 
 cflags-$(CONFIG_CPU_RM7000)	+= \