HID: mcp2221: switch i2c registration to devm functions

Switch from i2c_add_adapter() to resource managed devm_i2c_add_adapter()
for matching rest of driver initialization, and more concise code.

Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>