HID: cp2112: support large i2c transfers

cp2112_i2c_xfer() only reads up to 61 bytes, returning EIO on longers reads.
The fix is to wrap a loop around cp2112_read() to pick up all the returned
data.

Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>