remove NAN selection, better do it in your build system

With older gcc than 4.9.x, this breaks the build.
These specific compiler flags belongs better to your
favorite build system.

Rules.mak

@@ -404,10 +404,6 @@ ifeq ($(TARGET_ARCH),mips)
 	CPU_CFLAGS-$(CONFIG_MIPS_N64_ABI)+=-mabi=64
 	CPU_CFLAGS-$(CONFIG_MIPS_O32_ABI)+=-mabi=32
 	CPU_CFLAGS-$(CONFIG_MIPS_N32_ABI)+=-mabi=n32
-
-	CPU_CFLAGS-$(CONFIG_MIPS_NAN_LEGACY)+=-mnan=legacy
-	CPU_CFLAGS-$(CONFIG_MIPS_NAN_2008)+=-mnan=2008
-
 	CPU_LDFLAGS-y += $(CPU_CFLAGS)
 endif
 

extra/Configs/Config.mips

@@ -32,21 +32,6 @@ config CONFIG_MIPS_N64_ABI
 
 endchoice
 
-choice
-	prompt "Target NAN Encoding"
-	default CONFIG_MIPS_NAN_LEGACY
-	help
-	  This is the NAN Encoding you want to use.  Chose either Legacy
-	  or 2008.
-
-config CONFIG_MIPS_NAN_LEGACY
-	bool "LEGACY"
-
-config CONFIG_MIPS_NAN_2008
-	bool "2008"
-
-endchoice
-
 choice
 	prompt "Target Processor Architecture"
 	default CONFIG_MIPS_ISA_1 if CONFIG_MIPS_O32_ABI