[media] vivid: fix HDMI VSDB block in the EDID

The maximum 'Max TMDS Rate' in the HDMI VSDB block is 340 MHz, not 600.
Higher rates are advertised in the HDMI Forum VSDB block.

So lower the Max TMDS rate in the HDMI VSDB block that the vivid driver
uses to 300 MHz, which is typical of most HDMI 1.4b devices.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>