HID: i2c-hid: print the correct data in dbg msg

Report is received in "buffer"; fix the following i2c_hid_dbg()
to dump data from the correct pointer.

Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
[Antonio Borneo: cleanup and rebase to v3.17]
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>