ARM: dts: aspeed-g5: Fixe gpio-ranges upper limit

According to the AST2500/AST2520 specs, these SoCs support up to 228 GPIO
pins. However, 'gpio-ranges' value in 'aspeed-g5.dtsi' file is currently
setting the upper limit to 220 which isn't allowing access to all their
GPIOs. The correct upper limit value is 232 (actual number is 228 plus a
4-GPIO hole in GPIOAB). Without this patch, GPIOs AC5 and AC6 do not work
correctly on a AST2500 BMC running Linux Kernel v4.19

Fixes: 2039f90d ("ARM: dts: aspeed-g5: Add gpio controller to devicetree")
Signed-off-by: Oscar A Perez <linux@neuralgames.com>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>