pinctrl: Add pingroup and define PINCTRL_PINGROUP

Add 'struct pingroup' to represent pingroup and 'PINCTRL_PINGROUP'
macro for inline use. Both are used to manage and represent
larger number of pingroups.

Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220601152900.1012813-2-Basavaraj.Natikar@amd.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>