media: adv7842: support EDIDs up to 4 blocks

The adv7842 driver didn't support EDIDs of 3 or 4 blocks, even though the
hardware supports this.

It is a bit more complicated due to the fact that the adv7842 can expose
two EDIDs: one digital, one analog, for DVI-I connectors. In that case the
VGA_EDID_ENABLE bit is set and blocks 0 and 1 of the EDID eeprom are used
for the DVI-D part and block 2 is used for the DVI-A part of the DVI-I
connector.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>