staging: comedi: dyna_pci10xx: usleep_range is preferred over udelay

Fix the checkpatch.pl issue:
CHECK: usleep_range is preferred over udelay

Signed-off-by: Saber Rezvani <irsaber@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>