media: dvb: earth-pt1: replace schedule_timeout with usleep_range

As described in Document/timers/timers-howto.txt,
hrtimer-based delay should be used for small sleeps.

Signed-off-by: Akihiro Tsukada <tskd08@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>