staging: comedi: mite: use ilog2()

The static inline functions `MITE_IODWBSR_1_WSIZE_bits()` and `CR_RL()`
in "mite.h" work out a base-2 logarithm using a `while` loop.  Change
them to use `ilog2()`.  Also change `CR_RL()` to clamp the maximum value
instead of printing an error.

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