soc: sunxi: sram: Add updated compatible string for A64 system control

The SRAM mapping controls on Allwinner SoCs is located in a block called
"System Controls". This block also has registers for identifying the SoC,
reading the state of an external boot-related pin, and on some newer SoCs,
glue layer controls for the EMAC Ethernet controller.

The A64 variant compatible is renamed to "allwinner,a64-system-control"
to reflect this. The old A64 compatible is deprecated. So far we haven't
seen any actual use of it.

Acked-by: Maxime Ripard <[e-mail]>
Signed-off-by: Chen-Yu Tsai <[e-mail]>

drivers/soc/sunxi/sunxi_sram.c

···
 		.compatible = "allwinner,sun50i-a64-sram-controller",
 		.data = &sun50i_a64_sramc_variant,
 	},
+	{
+		.compatible = "allwinner,sun50i-a64-system-control",
+		.data = &sun50i_a64_sramc_variant,
+	},
 	{ },
 };
 MODULE_DEVICE_TABLE(of, sunxi_sram_dt_match);