V4L/DVB (5102): make videodev to auto-generate standards

v4l2_tvnorm were meant to describe video standards and its names to V4L2 API.
However, this were doing by some static structures at the driver.

This patch changes the internals in a way that, at the driver, only a
v4l2_tvnorm (a 64 bit integer) should be filled, with all supported
tvnorms. videodev will dynamically generate the proper API array
based on supported standards.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>