On cx88 driver, sampling rate should be at chroma subcarrier freq (FSC).
However, driver were programming wrong values for PAL/60, PAL/Nc and
NTSC 4.43. This patch do the proper calculation. It also calculates
htotal, hdelay and hactive constants, according with the sampling
rate.
It is tested with PAL/60 by Piotr Maksymuk and Olivier. Also tested with
the already-supported standards.

Test is still required for PAL/Nc.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>