Makefiles: Use $(MAINBOARD_DIR) instead of $(CONFIG_MAINBOARD_DIR)

The variable MAINBOARD_DIR already has the quotes stripped off.

Change-Id: Ib434ce92bdbc49180fb3f713b26d65ba4cf8c441
Signed-off-by: Martin Roth <martinroth@chromium.org>
Reviewed-on: https://review.coreboot.org/16117
Tested-by: build bot (Jenkins)
Reviewed-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/soc/intel/braswell/Makefile.inc

@@ -57,7 +57,7 @@ CPPFLAGS_common += -I$(src)/soc/intel/braswell/
 CPPFLAGS_common += -I$(src)/soc/intel/braswell/include
 CPPFLAGS_common += -I$(src)/vendorcode/intel/fsp/fsp1_1/braswell
 
-CPPFLAGS_common += -I3rdparty/blobs/mainboard/$(CONFIG_MAINBOARD_DIR)
+CPPFLAGS_common += -I3rdparty/blobs/mainboard/$(MAINBOARD_DIR)
 
 ifneq ($(CONFIG_GOP_SUPPORT),y)
 ifneq ($(CONFIG_VGA_BIOS_FILE),)

src/soc/intel/skylake/Makefile.inc

@@ -89,7 +89,7 @@ CPPFLAGS_common += -I$(src)/soc/intel/skylake/include
 CPPFLAGS_common += -I$(src)/vendorcode/intel/fsp/fsp1_1/skylake
 
 # Currently used for microcode path.
-CPPFLAGS_common += -I3rdparty/blobs/mainboard/$(CONFIG_MAINBOARD_DIR)
+CPPFLAGS_common += -I3rdparty/blobs/mainboard/$(MAINBOARD_DIR)
 
 ROMCCFLAGS := -mcpu=p4 -fno-simplify-phi -O2