ARM: armv7: refactor Makefile slightly

Use Kbuild standard style where possible.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/cpu/armv7/Makefile

@@ -18,15 +18,8 @@ obj-y	+= lowlevel_init.o
 endif
 endif
 
-ifneq ($(CONFIG_ARMV7_NONSEC),)
-obj-y	+= nonsec_virt.o
-obj-y	+= virt-v7.o
-obj-y	+= virt-dt.o
-endif
-
-ifneq ($(CONFIG_ARMV7_PSCI),)
-obj-y	+= psci.o
-endif
+obj-$(CONFIG_ARMV7_NONSEC)	+= nonsec_virt.o virt-v7.o virt-dt.o
+obj-$(CONFIG_ARMV7_PSCI)	+= psci.o
 
 obj-$(CONFIG_IPROC) += iproc-common/
 obj-$(CONFIG_KONA) += kona-common/