[media] m88ds3103: use Hz instead of kHz on calculations

There was some calculations where was kHz used in order to keep
calculation withing 32-bit. Convert all to Hz and use 64-bit
division helpers where needed.

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