staging: gpib: Use min for calculating transfer length

staging: gpib: Use min for calculating transfer length

In the accel read and write functions the transfer length
was being calculated by an if statement setting it to
the lesser of the remaining bytes to read/write and the
fifo size.

Replace both instances with min() which is clearer and
more compact.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@inria.fr>
Closes: https://lore.kernel.org/r/202501182153.qHfL4Fbc-lkp@intel.com/
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250120145030.29684-1-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>