allwinner: H6: Fix SRAM size

The SRAM in the Allwinner H6 SoC starts at 0x2000, with the last part
ending at 0x117fff (although with gaps in between).
So SUNXI_SRAM_SIZE should be 0xf8000, not 0x98000.

Fix this to map the arisc exception vector area, which we will need
shortly.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

plat/allwinner/sun50i_h6/include/sunxi_mmap.h

@@ -11,7 +11,7 @@
 #define SUNXI_ROM_BASE			0x00000000
 #define SUNXI_ROM_SIZE			0x00010000
 #define SUNXI_SRAM_BASE			0x00020000
-#define SUNXI_SRAM_SIZE			0x00098000
+#define SUNXI_SRAM_SIZE			0x000f8000
 #define SUNXI_SRAM_A1_BASE		0x00020000
 #define SUNXI_SRAM_A1_SIZE		0x00008000
 #define SUNXI_SRAM_A2_BASE		0x00104000