sunxi: add config for SPL at 0x20000 on H6

On the new Allwinner H6 SoC, the SRAM A2 address (SPL load address) is
at 0x20000, which is different with any old Allwinner SoCs.

Add SPL position and size configuration for this.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>

include/configs/sunxi-common.h

@@ -196,6 +196,11 @@
 #else
 #define LOW_LEVEL_SRAM_STACK		0x00018000
 #endif /* !CONFIG_ARM64 */
+#elif CONFIG_SUNXI_SRAM_ADDRESS == 0x20000
+#define CONFIG_SPL_TEXT_BASE		0x20060		/* sram start+header */
+#define CONFIG_SPL_MAX_SIZE		0x7fa0		/* 32 KiB */
+/* end of SRAM A2 on H6 for now */
+#define LOW_LEVEL_SRAM_STACK		0x00118000
 #else
 #define CONFIG_SPL_TEXT_BASE		0x60		/* sram start+header */
 #define CONFIG_SPL_MAX_SIZE		0x5fa0		/* 24KB on sun4i/sun7i */