HID: mcp2221: add usb to i2c-smbus host bridge

MCP2221 is a USB HID to I2C/SMbus host bridge device. This
commit implements i2c and smbus host adapter support. 7-bit
address and i2c multi-message transaction is also supported.

Signed-off-by: Rishi Gupta <gupt21@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>