pistachio: add generic subtarget

Same game as for 853e4dd3062df7cb5704b15d6af6730e3194b571. Add generic
to the filenames.

Signed-off-by: Christian Marangi <[email protected]>

target/linux/pistachio/Makefile

@@ -10,6 +10,7 @@ BOARDNAME:=MIPS pistachio
 FEATURES:=fpu usb usbgadget squashfs targz nand
 CPU_TYPE:=24kc
 CPU_SUBTYPE:=24kf
+SUBTARGETS:=generic
 
 KERNEL_PATCHVER:=5.10
 

target/linux/pistachio/generic/target.mk

@@ -0,0 +1 @@
+BOARDNAME:=Generic