pinctrl: Rename pinctrl_utils_dt_free_map to pinctrl_utils_free_map

Rename pinctrl_utils_dt_free_map to pinctrl_utils_free_map, since
it does not depend on device tree despite the current name. This
will enforce a consistent naming in pinctr-utils.c and will make
it clear it can be called from outside device tree (e.g. from
ACPI handling code).

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>