dt-bindings: pinctrl: brcm,bcm11351-pinctrl: Convert to YAML

Convert Broadcom BCM281xx pin controller bindings to DT schema.

Signed-off-by: Stanislav Jakubek <stano.jakubek@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/ZMZ3aEnrrZRDNdO+@standask-GA-A55M-S2HP


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>