pinctrl: samsung: Parse pin groups before calling pinctrl_register()

Calling pinctrl_register() means that the driver is fully initialized
and might accept pinmux/pinconf requests, so pin groups must be parsed
before.

This patch fixes this problem by moving device tree parsing before call
to pinctrl_register(). In addition, this fixes support for hogs on
pin controllers handled by pinctrl-samsung driver.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>