arm64: dts: Fix gpio to pinmux mapping

There are total of 151 non-secure gpio (0-150) and four
pins of pinmux (91, 92, 93 and 94) are not mapped to any
gpio pin, hence update same in DT.

Fixes: 8aa428cc ("arm64: dts: Add pinctrl DT nodes for Stingray SOC")
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>