build: add config option KERNEL_MIPS_FPU_EMULATOR

To make it more accessible for nodejs users to configure and run a build
on mips target lacking hardware fpu

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

config/Config-kernel.in

@@ -42,6 +42,11 @@ config KERNEL_DEBUG_FS
 	  write to these files. Many common debugging facilities, such as
 	  ftrace, require the existence of debugfs.
 
+config KERNEL_MIPS_FPU_EMULATOR
+	bool "Compile the kernel with MIPS FPU Emulator"
+	default (TARGET_lantiq_ase || TARGET_pistachio)
+	depends on (mips || mipsel || mips64 || mips64el)
+
 config KERNEL_ARM_PMU
 	bool
 	default n

target/linux/lantiq/ase/config-default

@@ -11,7 +11,6 @@ CONFIG_GPIO_GENERIC_PLATFORM=y
 # CONFIG_ISDN is not set
 # CONFIG_LBDAF is not set
 CONFIG_LEDS_TRIGGER_HEARTBEAT=y
-CONFIG_MIPS_FPU_EMULATOR=y
 CONFIG_NLS=y
 # CONFIG_PSB6970_PHY is not set
 # CONFIG_RTL8366_SMI is not set

target/linux/pistachio/config-4.9

@@ -186,7 +186,6 @@ CONFIG_MIPS_CPS_PM=y
 CONFIG_MIPS_CPU_SCACHE=y
 # CONFIG_MIPS_ELF_APPENDED_DTB is not set
 CONFIG_MIPS_EXTERNAL_TIMER=y
-CONFIG_MIPS_FPU_EMULATOR=y
 CONFIG_MIPS_GIC=y
 # CONFIG_MIPS_HUGE_TLB_SUPPORT is not set
 CONFIG_MIPS_L1_CACHE_SHIFT=5