pinctrl: samsung: Assing pin numbers dynamically

This patch modifies the pinctrl-samsung driver to assign numbers to pins
dynamically instead of static enumerations.

Thanks to this change the amount of code requried to support a SoC can
be greatly reduced and the code made more readable.

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