V4L/DVB (6027): Get rid of an ill-behaved msleep in i2c write

Configuring the OLPC camera requires something over 150 register
writes.  Unfortunately, querying the CAFE i2c controller too
soon after a write causes the hardware to flake.  The problem had
been "solved" with an msleep() call, but, between the number of
registers and how msleep() behaves, that resulted in a 3-second
delay on camera initialization.  Instead, we hand-code a wait for
the completion interrupt which avoids reading the status registers.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>