scripts/gdb: do not descend into scripts/gdb from scripts

Currently, Kbuild descends from scripts/Makefile to scripts/gdb/Makefile
just for creating symbolic links, but it does not need to do it so early.

Merge the two descending paths to simplify the code.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
diff --git a/Makefile b/Makefile
index 15a9987..d05da1b 100644
--- a/Makefile
+++ b/Makefile
@@ -1524,7 +1524,7 @@
 
 PHONY += scripts_gdb
 scripts_gdb: prepare
-	$(Q)$(MAKE) $(build)=scripts/gdb/linux build_constants_py
+	$(Q)$(MAKE) $(build)=scripts/gdb
 
 ifdef CONFIG_GDB_SCRIPTS
 all: scripts_gdb