checks: tigthen up nr-gpios prop exception

There are no instances of nr-gpio in the Linux kernel tree, only
"[<vendor>,]nr-gpios", so make the check stricter.

nr-gpios without a "vendor," prefix is also invalid, according to the DT
spec[0], and there are no DT files in the Linux kernel tree with
non-vendor nr-gpios. There are some drivers, but they are not DT spec
compliant, so don't suppress the check for them.

[0]:
Link: https://github.com/devicetree-org/dt-schema/blob/cb53a16a1eb3e2169ce170c071e47940845ec26e/schemas/gpio/gpio-consumer.yaml#L20

Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Message-Id: <20210504035944.8453-2-ilya.lipnitskiy@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
1 file changed