qlcnic: Use usleep_range() instead of msleep() for sleep less than 20ms

As per recommendation, msleep() may sleep longer than intended time for
values less than 20ms. So, use usleep_range() instead of msleep()

Signed-off-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>