media: dvb_ca_en50221: use usleep_range

Fixed all:
  WARNING: msleep < 20ms can sleep for up to 20ms
by using usleep_range.

Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>