Blackfin arch: as pointed out by Robert P. J. Day, update the CPU_FREQ name to match current Kconfig

Cc: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

arch/blackfin/mach-bf533/Makefile

@@ -6,4 +6,4 @@ extra-y := head.o
 
 obj-y := ints-priority.o dma.o
 
-obj-$(CONFIG_CPU_FREQ_BF533) += cpu.o
+obj-$(CONFIG_CPU_FREQ)   += cpu.o