dt-bindings: mfd: Fix pinctrl node name warnings

The recent addition pinctrl.yaml in commit c09acbc4 ("dt-bindings:
pinctrl: use pinctrl.yaml") resulted in some node name warnings:

Documentation/devicetree/bindings/mfd/cirrus,lochnagar.example.dt.yaml: \
 lochnagar-pinctrl: $nodename:0: 'lochnagar-pinctrl' does not match '^(pinctrl|pinmux)(@[0-9a-f]+)?$'
Documentation/devicetree/bindings/mfd/cirrus,madera.example.dt.yaml: \
 codec@1a: $nodename:0: 'codec@1a' does not match '^(pinctrl|pinmux)(@[0-9a-f]+)?$'
Documentation/devicetree/bindings/mfd/brcm,cru.example.dt.yaml: \
 pin-controller@1c0: $nodename:0: 'pin-controller@1c0' does not match '^(pinctrl|pinmux)(@[0-9a-f]+)?$'

Fix the node names to the preferred 'pinctrl'. For cirrus,madera,
nothing from pinctrl.yaml schema is used, so just drop the reference.

Fixes: c09acbc4 ("dt-bindings: pinctrl: use pinctrl.yaml")
Cc: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220303232350.2591143-1-robh@kernel.org