pinctrl: palmas: Fix device name in Kconfig text

The device family is called Palmas so there should be a 's' on the end of
the name.

Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>