i2cdetect: fix address skipping in auto mode

i2cdetect: fix address skipping in auto mode

If the bus doesn't support SMBus Quick Write or Receive Byte commands
and we're running in auto mode all addresses will be skipped resulting
in an empty table being printed.

This is caused by not restoring the auto mode after it's been changed
for certain address ranges - we need an additional variable to hold the
temporary state.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>