I was hoping we could detect I2C devices at a given address without
actually writing data into them, but apparently some DDC slaves get
confused with 0-bytes transactions. Put the good old test back.
Reported-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>