powerpc: make syntax for FADump config options in kernel/Makefile readable

arch/powerpc/kernel/fadump.c file needs to be compiled in if 'config
FA_DUMP' or 'config PRESERVE_FA_DUMP' is set. The current syntax
achieves that but looks a bit odd. Fix it for better readability.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/157063484064.11906.3586824898111397624.stgit@hbathini.in.ibm.com

arch/powerpc/kernel/Makefile

@@ -78,9 +78,8 @@ obj-$(CONFIG_EEH)              += eeh.o eeh_pe.o eeh_dev.o eeh_cache.o \
 				  eeh_driver.o eeh_event.o eeh_sysfs.o
 obj-$(CONFIG_GENERIC_TBSYNC)	+= smp-tbsync.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
-ifneq ($(CONFIG_FA_DUMP)$(CONFIG_PRESERVE_FA_DUMP),)
-obj-y				+= fadump.o
-endif
+obj-$(CONFIG_FA_DUMP)		+= fadump.o
+obj-$(CONFIG_PRESERVE_FA_DUMP)	+= fadump.o
 ifdef CONFIG_PPC32
 obj-$(CONFIG_E500)		+= idle_e500.o
 endif