staging: comedi/daqboard2000: use mdelay for large delays

On ARM, it is not legal to pass values larger than 2ms into udelay(),
and mdelay() must be used instead, to avoid this build error:

ERROR: "__bad_udelay" [drivers/staging/comedi/drivers/daqboard2000.ko]
undefined!

On a related note, any use of mdelay() or large udelay() numbers should
be carefully reviewed, and replaced with msleep() or a different
implementation that does not rely on delaying the work.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>