ramips/rt288x: switch CPU_TYPE to 24kc

While rt288x only has a MIPS 4KEc processor, it implements the MIPS32r2
architecture just like the 24Kc, so the instruction set should be 100%
compatible.
Switching it to 24kc allows it to share the package architecture with a
lot of other targets instead of creating a special case, saving
buildbot resources.

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

target/linux/ramips/rt288x/target.mk

@@ -4,7 +4,7 @@
 
 SUBTARGET:=rt288x
 BOARDNAME:=RT288x based boards
-CPU_TYPE:=mips32r2
+CPU_TYPE:=24kc
 
 DEFAULT_PACKAGES += kmod-rt2800-soc