V4L/DVB (4915): Saa7146: Add timeout protection for I2C interrupt

Add a timeout to the wait for the i2c-interrupt.
The timeout prevents from endless waiting if the
interrupt gets lost.

Signed-off-by: Hartmut Birr <e9hack@googlemail.com>
Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>