pinctrl: imx: Reduce printk message level for empty nodes

iomuxc_snvs from imx6ull supports 2 boot mode and 10 tamper pins.
Probably most users won't use them, causing this error message during boot:
  no groups defined in /soc/bus@2200000/iomuxc-snvs@2290000
This is actually not an error in this case, so reduce the level
accordingly.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://lore.kernel.org/r/20220224094243.1376965-1-alexander.stein@ew.tq-group.com


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