ARM: dts: stm32: omit unused pinctrl groups from stm32mp13 dtb files

ARM: dts: stm32: omit unused pinctrl groups from stm32mp13 dtb files

stm32mp13-pinctrl.dtsi contains nearly all pinctrl groups collected from
all boards. Most of them end up unused by a board and only waste binary
space. Add /omit-if-no-ref/ to the groups to scrub the unused groups
from the dtbs.

Use the following regex to update the file and drop two useless newlines too:
s@^\t[^:]\+: [^ ]\+ {$@\t/omit-if-no-ref/\r&@

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>