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/microblaze/lib/Makefile b/arch/microblaze/lib/Makefile
index dfd8135..2f23482 100644
--- a/arch/microblaze/lib/Makefile
+++ b/arch/microblaze/lib/Makefile
@@ -3,6 +3,6 @@
 # (C) Copyright 2003-2006
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-obj-$(CONFIG_CMD_BOOTM) += bootm.o
+obj-$(CONFIG_BOOTM) += bootm.o
 obj-$(CONFIG_CMD_BDI) += bdinfo.o
 obj-y	+= muldi3.o