net: dsa: lan9303: Replace msleep(1) with usleep_range()

Remove scripts/checkpatch.pl WARNING by replacing msleep(1) with usleep_range()

Signed-off-by: Egil Hjelmeland <privat@egil-hjelmeland.no>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>