IB: Convert msleep below 20ms to usleep_range

The msleep(1) may do not sleep 1 ms as expected
and will sleep longer. The simple conversion from
msleep to usleep_range between 1ms and 2ms can solve an
issue.

The full and comprehensive explanation can be found at [1] and [2].

[1] https://lkml.org/lkml/2007/8/3/250


[2] Documentation/timers/timers-howto.txt

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>