sunxi: change SUNXI_HIGH_SRAM option to SUNXI_SRAM_ADDRESS

sunxi: change SUNXI_HIGH_SRAM option to SUNXI_SRAM_ADDRESS

The new Allwinner H6 SoC has its SRAM A1 at neither 0x0 nor 0x10000, but
it's at 0x20000. Thus the SUNXI_HIGH_SRAM option needs to be refactored
to support this new configuration.

Change it to SUNXI_SRAM_ADDRESS, which holds the real address of SRAM
A1 in the memory map.

Signed-off-by: Icenowy Zheng <[email protected]>
Reviewed-by: Andre Przywara <[email protected]>
Acked-by: Maxime Ripard <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>
Tested-by: Jagan Teki <[email protected]>