V4L/DVB (4124): Kconfig: fix description for saa7115 module

This Kconfig description is incorrect, due to a previous merge a while back.
CONFIG_SAA711X builds module saa7115, which is the newer module, and is
not obsoleted.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>