powerpc: rename powermac files to remove pmac_ prefix

Since the files are now in arch/powerpc/platforms/powermac, the
pmac_ prefix that they had is redundant.
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/powermac/Makefile

-obj-$(CONFIG_PPC_PMAC)		+= pmac_pic.o pmac_setup.o pmac_time.o \
-				   pmac_feature.o pmac_pci.o pmac_sleep.o \
-				   pmac_low_i2c.o pmac_cache.o
-obj-$(CONFIG_PMAC_BACKLIGHT)	+= pmac_backlight.o
-obj-$(CONFIG_CPU_FREQ_PMAC)	+= pmac_cpufreq.o
+obj-$(CONFIG_PPC_PMAC)		+= pic.o setup.o time.o feature.o pci.o \
+				   sleep.o low_i2c.o cache.o
+obj-$(CONFIG_PMAC_BACKLIGHT)	+= backlight.o
+obj-$(CONFIG_CPU_FREQ_PMAC)	+= cpufreq.o
 ifeq ($(CONFIG_PPC_PMAC),y)
-obj-$(CONFIG_NVRAM)		+= pmac_nvram.o
-obj-$(CONFIG_SMP)		+= pmac_smp.o
+obj-$(CONFIG_NVRAM)		+= nvram.o
+obj-$(CONFIG_SMP)		+= smp.o
 endif