microblaze: Do not use _start in vmlinux

_start symbol stores physical address where kernel is.
Gdb uses this symbol for their purpose that's why
we have to rename it.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/boot/Makefile b/arch/microblaze/boot/Makefile
index 745a7f1..be01d78 100644
--- a/arch/microblaze/boot/Makefile
+++ b/arch/microblaze/boot/Makefile
@@ -35,7 +35,7 @@
 	cmd_cp = cat $< >$@$2 || (rm -f $@ && echo false)
 
 quiet_cmd_strip = STRIP   $@
-	cmd_strip = $(STRIP) -K _start -K _end -K __log_buf \
+	cmd_strip = $(STRIP) -K microblaze_start -K _end -K __log_buf \
 				-K _fdt_start vmlinux -o $@
 
 quiet_cmd_uimage = UIMAGE  $@.ub