kernel: backport MIPS changes introducing a separate IRQ stack

Prevents crashes when IRQs arrive when the current kernel stack context
already contains deeply nested function calls, e.g. when stacking lots
of network devices on top of each other

Signed-off-by: Felix Fietkau <nbd@nbd.name>

target/linux/generic/patches-4.4/304-mips_disable_fpu.patch

@@ -26,7 +26,7 @@ v2: incorporated changes suggested by Jonas Gorski
 
 --- a/arch/mips/Kconfig
 +++ b/arch/mips/Kconfig
-@@ -2724,6 +2724,20 @@ config MIPS_O32_FP64_SUPPORT
+@@ -2725,6 +2725,20 @@ config MIPS_O32_FP64_SUPPORT
  
  	  If unsure, say N.