refactor(Makefile): move NEED_<IMAGE> before their use

In later patch tbbr_tools.mk requires NEED_BL2 definition which is
defined after inclusion of this mk file.
Move NEED_<IMAGE> definitions earlier to their use

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ieff999b255690755779d0cd35d5aba2d3794873c
diff --git a/Makefile b/Makefile
index 59d14ba..ef81597 100644
--- a/Makefile
+++ b/Makefile
@@ -776,10 +776,16 @@
 # Process platform overrideable behaviour
 ################################################################################
 
-# Using BL2 implies that a BL33 image also needs to be supplied for the FIP and
-# Certificate generation tools. This flag can be overridden by the platform.
+ifdef BL1_SOURCES
+NEED_BL1 := yes
+endif
+
 ifdef BL2_SOURCES
-        ifdef EL3_PAYLOAD_BASE
+	NEED_BL2 := yes
+
+	# Using BL2 implies that a BL33 image also needs to be supplied for the FIP and
+	# Certificate generation tools. This flag can be overridden by the platform.
+	ifdef EL3_PAYLOAD_BASE
                 # If booting an EL3 payload there is no need for a BL33 image
                 # in the FIP file.
                 NEED_BL33		:=	no
@@ -794,6 +800,10 @@
         endif
 endif
 
+ifdef BL2U_SOURCES
+NEED_BL2U := yes
+endif
+
 # If SCP_BL2 is given, we always want FIP to include it.
 ifdef SCP_BL2
         NEED_SCP_BL2		:=	yes
@@ -831,6 +841,10 @@
 FIP_ARGS += --align ${FIP_ALIGN}
 endif
 
+ifdef FDT_SOURCES
+NEED_FDT := yes
+endif
+
 ################################################################################
 # Include libraries' Makefile that are used in all BL
 ################################################################################
@@ -874,30 +888,22 @@
 ################################################################################
 # Include BL specific makefiles
 ################################################################################
-ifdef BL1_SOURCES
-NEED_BL1 := yes
+
+ifeq (${NEED_BL1},yes)
 include bl1/bl1.mk
 endif
 
-ifdef BL2_SOURCES
-NEED_BL2 := yes
+ifeq (${NEED_BL2},yes)
 include bl2/bl2.mk
 endif
 
-ifdef BL2U_SOURCES
-NEED_BL2U := yes
+ifeq (${NEED_BL2U},yes)
 include bl2u/bl2u.mk
 endif
 
 ifeq (${NEED_BL31},yes)
-ifdef BL31_SOURCES
 include bl31/bl31.mk
 endif
-endif
-
-ifdef FDT_SOURCES
-NEED_FDT := yes
-endif
 
 ################################################################################
 # Build options checks