sh-pfc: Guard DT parsing with #ifdef CONFIG_OF

sh-pfc: Guard DT parsing with #ifdef CONFIG_OF

Fix a compilation error caused by pinconf_generic_parse_dt_config() not
being defined on !CONFIG_OF platforms by guarding the whole DT node
parsing code with #ifdef CONFIG_OF.

Defining a pinconf_generic_parse_dt_config() on !CONFIG_OF would have
been possible as well, but would have resulted in a larger code size on
!CONFIG_OF platforms (such as arch/sh).

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>