This reverts commit ff83bd82.

As requested by Antti:
From a talk with him at #linuxtv irc, he strong feeling that some apps
like MythTV will do a lot a lot of I2C I/O and now it adds locks,
with utimatelly means more delays. This could cause bad effects.

There is a new patch for 3.3 that re-writes af9013 in order to limit
I2C I/O. and thus those patches could be nice to have together
because those user who has has problems are most likely MythTV users.

So, let's revert this commit for now.
Requested-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>