treewide: Make arch-specific bootm code depend on BOOTM

Allow these functions to be compiled in when CONFIG_BOOTM is enabled,
even if CONFIG_CMD_BOOTM is not.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Angelo Dureghello <angelo@kernel-space.org>
diff --git a/arch/sh/lib/Makefile b/arch/sh/lib/Makefile
index e7520a3..8c3c302 100644
--- a/arch/sh/lib/Makefile
+++ b/arch/sh/lib/Makefile
@@ -6,7 +6,7 @@
 extra-y	+= start.o
 
 obj-y	+= board.o
-obj-$(CONFIG_CMD_BOOTM) += bootm.o
+obj-$(CONFIG_BOOTM) += bootm.o
 obj-y	+= time.o
 obj-$(CONFIG_CMD_SH_ZIMAGEBOOT) += zimageboot.o