staging: gpib: mite: remove unused global functions

The mite.c file was originally copied from the COMEDI code, and now that
it is in the kernel tree, along with the comedi code, on some build
configurations there are errors due to duplicate symbols (specifically
mite_dma_disarm).

Remove all of the unused functions in the gpib mite.c and .h files as
they aren't needed and cause the compiler to be confused.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202501081239.BAPhfAHJ-lkp@intel.com/


Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/2025010809-padding-survive-91b3@gregkh


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>