initramfs: shorten cmd_initfs in usr/Makefile

Avoid repetition of long variables.

No functional change intended.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>

usr/Makefile

@@ -62,8 +62,8 @@ $(deps_initramfs): ;
 quiet_cmd_initfs = GEN     $@
       cmd_initfs = \
 	$(CONFIG_SHELL) $< -o $@ -l $(obj)/.initramfs_data.cpio.d \
-	$(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
-	$(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID)) \
+	$(addprefix -u , $(CONFIG_INITRAMFS_ROOT_UID)) \
+	$(addprefix -g , $(CONFIG_INITRAMFS_ROOT_GID)) \
 	$(if $(KBUILD_BUILD_TIMESTAMP), -d "$(KBUILD_BUILD_TIMESTAMP)") \
 	$(ramfs-input)