Some device trees use pinctrl-* settings inside device tree nodes for
clock providers.

Barebox does not threat clock providers (such as fixed-clock or
gpio-gate-clock) as conventional devices, thus setting default
pinctrl configuration in driver binding code does not happen for
clock providers.

This patch adds setting default pinctrl configuration to of_clk_init(),
just before calling clock provider's probe routine.

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>