ath25: add generic subtarget

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

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

target/linux/ath25/Makefile

@@ -8,6 +8,7 @@ ARCH:=mips
 BOARD:=ath25
 BOARDNAME:=Atheros AR231x/AR5312
 FEATURES:=squashfs low_mem small_flash
+SUBTARGETS:=generic
 
 KERNEL_PATCHVER:=5.10
 KERNEL_TESTING_PATCHVER:=5.10

target/linux/ath25/generic/target.mk

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