[U-Boot] [PATCH] Makefile: Add the missing dependency for spl target

[Aneesh V]

Wolfgang's patch for build time improvement is bringing
out issues due to missing dependencies in the top-level
Makefile. I get errors such as the below while building
with many threads.

make[1]: /home/a0393566local/u-boot-denx/tools/mkimage: Command not found

This also allows one to do:
$ make spl/u-boot-spl.bin
if you want to build only spl

Cc: Wolfgang Denk <wd at denx.de>
Signed-off-by: Aneesh V <aneesh at ti.com>
---
 Makefile |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index 82de62b..7ae8b22 100644
--- a/Makefile
+++ b/Makefile
@@ -481,7 +481,7 @@ mmc_spl:	$(TIMESTAMP_FILE) $(VERSION_FILE) depend
 
 $(obj)mmc_spl/u-boot-mmc-spl.bin:	mmc_spl
 
-$(obj)spl/u-boot-spl.bin:		depend
+$(obj)spl/u-boot-spl.bin:	$(SUBDIR_TOOLS) depend
 		$(MAKE) -C spl all
 
 updater:
-- 
1.7.1