V4L/DVB (10977): STB6100 init fix, the call to stb6100_set_bandwidth needs an argument

in Hz not kHz, and a comment incorrectly says MHz instead of Hz. I
don't know if this caused real problems anywhere

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>