media: dib0700: fix error handling in dib0700_i2c_xfer_legacy()

Mostly this adds some unlocks to error paths.  But, if you see where
there were "break;" statements before, I changed those paths to return
error codes instead of returning success.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>