pinctrl: artpec6: dt: add missing pin group uart5nocts

Add missing pin group uart5nocts (all pins except cts), which has been
supported by the artpec6 pinctrl driver since its initial submission.

Fixes: 00df0582 ("pinctrl: Add pincontrol driver for ARTPEC-6 SoC")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>