[media] em28xx-i2c: also print debug messages at debug level 1

The current code uses only a single debug level and all debug messages are
printed for i2c_debug >= 2 only. So debug level 1 is actually the same as
level 0, which is odd.
Users expect debugging messages to become enabled for anything else than
debug level 0.
Fix it and simplify the code a bit by printing the debug messages also at debug
level 1;

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>