pinctrl: capri: add dependency on OF

As this driver is using pinconf_generic_dt_node_to_map_pin() it
needs to depend on OF so as not to cause build problems on
archs that do not support OF.

Cc: Sherman Yin <syin@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>