Make: fix dependency files generation

Currently, if no make goal is specified in the command line, 'all'
is assumed by default, but the dependency files are not generated.
This might lead to a successful but inconsistent build. This patch
provides a fix to the problem.

Change-Id: I0148719e114dbdbe46f8a57c7d05da7cbc212c92

Makefile

@@ -34,6 +34,9 @@
 VERSION_MAJOR			:= 1
 VERSION_MINOR			:= 1
 
+# Default goal is build all images
+.DEFAULT_GOAL			:= all
+
 include make_helpers/build_macros.mk
 
 ################################################################################
@@ -375,9 +378,6 @@ endif
 # Build targets
 ################################################################################
 
-# Default target
-.DEFAULT_GOAL := all
-
 .PHONY:	all msg_start clean realclean distclean cscope locate-checkpatch checkcodebase checkpatch fiptool fip certtool
 .SUFFIXES:
 

make_helpers/build_macros.mk

@@ -112,6 +112,12 @@ endef
 # Auxiliary macros to build TF images from sources
 ################################################################################
 
+# If no goal is specified in the command line, .DEFAULT_GOAL is used.
+# .DEFAULT_GOAL is defined in the main Makefile before including this file.
+ifeq ($(MAKECMDGOALS),)
+MAKECMDGOALS := $(.DEFAULT_GOAL)
+endif
+
 define match_goals
 $(strip $(foreach goal,$(1),$(filter $(goal),$(MAKECMDGOALS))))
 endef