powerpc/perf: Simplify Makefile

arch/powerpc/Kbuild decend into arch/powerpc/perf/ only when
CONFIG_PERF_EVENTS is selected, so there is not need to take
CONFIG_PERF_EVENTS into account in arch/powerpc/perf/Makefile.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d37f61afca55b5b33787b643890e061ae1c18f5f.1620396045.git.christophe.leroy@csgroup.eu

arch/powerpc/perf/Makefile

 # SPDX-License-Identifier: GPL-2.0
 
-obj-$(CONFIG_PERF_EVENTS)	+= callchain.o callchain_$(BITS).o perf_regs.o
-ifdef CONFIG_COMPAT
-obj-$(CONFIG_PERF_EVENTS)	+= callchain_32.o
-endif
+obj-y				+= callchain.o callchain_$(BITS).o perf_regs.o
+obj-$(CONFIG_COMPAT)		+= callchain_32.o
 
 obj-$(CONFIG_PPC_PERF_CTRS)	+= core-book3s.o bhrb.o
 obj64-$(CONFIG_PPC_PERF_CTRS)	+= ppc970-pmu.o power5-pmu.o \