[media] tvp5150: Initialize the chip on probe

After power-up, the tvp5150 decoder is in a unknown state until the
RESETB pin is driven LOW which reset all the registers and restarts
the chip's internal state machine.

The init sequence has some timing constraints and the RESETB signal
can only be used if the PDN (Power-down) pin is first released.

So, the initialization sequence is as follows:

1- PDN (active-low) is driven HIGH so the chip is power-up
2- A 20 ms delay is needed before sending a RESETB (active-low) signal.
3- The RESETB pulse duration is 500 ns.
4- A 200 us delay is needed for the I2C client to be active after reset.

This patch used as a reference the logic in the IGEPv2 board file from
the ISEE 2.6.37 vendor tree.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>