Add proftool to decode profile data

This tool provides the facility to decode U-Boot trace data and write out
a text file in Linux ftrace format for use with pytimechart.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index fdaddb9..47ffb44 100644
--- a/Makefile
+++ b/Makefile
@@ -831,7 +831,8 @@
 	       $(obj)tools/mk{smdk5250,}spl				  \
 	       $(obj)tools/mxsboot					  \
 	       $(obj)tools/ncb		   $(obj)tools/ubsha1		  \
-	       $(obj)tools/kernel-doc/docproc
+	       $(obj)tools/kernel-doc/docproc				  \
+	       $(obj)tools/proftool
 	@rm -f $(obj)board/cray/L1/{bootscript.c,bootscript.image}	  \
 	       $(obj)board/matrix_vision/*/bootscript.img		  \
 	       $(obj)board/voiceblue/eeprom 				  \