allwinner: Reenable USE_COHERENT_MEM

Now that there is plenty of space (32 KiB) available for NOBITS
sections, we can afford using an entire page for coherent memory. In
fact, because it simplifies the code, this is a beneficial change for
loaded image (.text) size, where we are still close to the size limit.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Change-Id: I0b899dabcb162015c63b0e4aed0869569c889ed9
diff --git a/plat/allwinner/common/sunxi_common.c b/plat/allwinner/common/sunxi_common.c
index 1e21a42..cff8268 100644
--- a/plat/allwinner/common/sunxi_common.c
+++ b/plat/allwinner/common/sunxi_common.c
@@ -57,6 +57,10 @@
 	mmap_add_region(BL_RO_DATA_BASE, BL_RO_DATA_BASE,
 			BL_RO_DATA_END - BL_RO_DATA_BASE,
 			MT_RO_DATA | MT_SECURE);
+	mmap_add_region(BL_COHERENT_RAM_BASE, BL_COHERENT_RAM_BASE,
+			BL_COHERENT_RAM_END - BL_COHERENT_RAM_BASE,
+			MT_DEVICE | MT_RW | MT_SECURE | MT_EXECUTE_NEVER);
+
 	mmap_add(sunxi_mmap);
 	init_xlat_tables();