powerpc/64: Do not link crtsavres.o in vmlinux

The 64-bit linker creates save/restore functions on demand with final
links, so vmlinux does not require crtsavres.o.

Make crtsavres.o extra-y on 64-bit (it is still required by modules).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/lib/Makefile

@@ -9,8 +9,12 @@ ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
 CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
 
-obj-y += string.o alloc.o crtsavres.o code-patching.o \
-	 feature-fixups.o
+obj-y += string.o alloc.o code-patching.o feature-fixups.o
+
+# 64-bit linker creates .sfpr on demand for final link (vmlinux),
+# so it is only needed for modules.
+obj-$(CONFIG_PPC32) += crtsavres.o
+extra-$(CONFIG_PPC64) += crtsavres.o
 
 obj-$(CONFIG_PPC32)	+= div64.o copy_32.o