pinctrl: generic: free maps on pinctrl_generic_to_map() failure

In the Linux kernel, the following vulnerability has been resolved:

pinctrl: generic: free maps on pinctrl_generic_to_map() failure

pinctrl_generic_to_map() parses DT configuration and allocates pinctrl
maps via pinctrl_utils_reserve_map().

If subsequent steps (such as pinctrl_utils_add_map_mux(),
pinctrl_generic_add_group(), pinconf_generic_parse_dt_config(), or
pinctrl_utils_add_map_configs()) return an error, *maps may contain
partially allocated map entries. Returning the error directly without
freeing *maps leaks the allocated mapping memory across all drivers
that rely on pinctrl_generic_to_map().

Fix this by calling pinctrl_utils_free_map() and resetting *maps,
*num_maps, and *num_reserved_maps in the error path of
pinctrl_generic_to_map().