CONFIG: EXYNOS5: Replace misnomer SMDK5250 with EXYNOS5250 and update Makefiles

Update the Makefiles so that all boards can use the same spl generation tool

Signed-off-by: Inderpal Singh <inderpal.singh@linaro.org>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/Makefile b/Makefile
index 5461a21..488db8a 100644
--- a/Makefile
+++ b/Makefile
@@ -813,7 +813,7 @@
 	       $(obj)tools/gdb/{astest,gdbcont,gdbsend}			  \
 	       $(obj)tools/gen_eth_addr    $(obj)tools/img2srec		  \
 	       $(obj)tools/mk{env,}image   $(obj)tools/mpc86x_clk	  \
-	       $(obj)tools/mk{smdk5250,}spl				  \
+	       $(obj)tools/mk{$(BOARD),}spl				  \
 	       $(obj)tools/mxsboot					  \
 	       $(obj)tools/ncb		   $(obj)tools/ubsha1		  \
 	       $(obj)tools/kernel-doc/docproc				  \