Remove unneeded include paths in PLAT_INCLUDES

Also, update platform_def.h guidelines about includes in the porting
guide.

Change-Id: I1ae338c9dd3242b309f6d53687ba2cb755d488c3
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/hisilicon/poplar/platform.mk b/plat/hisilicon/poplar/platform.mk
index eca1412..a1535a4 100644
--- a/plat/hisilicon/poplar/platform.mk
+++ b/plat/hisilicon/poplar/platform.mk
@@ -53,8 +53,7 @@
 $(eval $(call add_define,PLAT_PL061_MAX_GPIOS))
 
 PLAT_INCLUDES	:=	-Iplat/hisilicon/poplar/include		\
-			-Iplat/hisilicon/poplar			\
-			-Iinclude/common/tbbr
+			-Iplat/hisilicon/poplar
 
 PLAT_BL_COMMON_SOURCES	:=						\
 		lib/xlat_tables/aarch64/xlat_tables.c			\