staging: gpib: Change // comments in uapi header file

staging: gpib: Change // comments in uapi header file

A ppc64 randconfig build complained about the // comments in the uapi
header file:
error: // comments are not allowed in this language [-Werror,-Wcomment]

Change the // comments to /* */ format.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511141203.sbp27oAR-lkp@intel.com/
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://patch.msgid.link/20251117144021.23569-2-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>