ARM: dts: bcm283x: Fix pinctrl groups

ARM: dts: bcm283x: Fix pinctrl groups

Currently the dtbs_check for bcm2837 generates warnings like this:

gpio@7e200000: 'pinctrl-0' is a dependency of 'pinctrl-names'

This is caused by the definition of pinctrl-names without matching
pinctrl group and vice versa. So defining both at the same place
make the dts files easier to review.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/20230617133620.53129-2-stefan.wahren@i2se.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>