staging: gpib: Rename common include file

User code includes gpib_user.h. Since this include has diverged
from the original by
  - removing unused functions and defines
  - changing camel-case identifiers
  - removing typedefs
we need to change the name of the kernel include. This include
will be included in the userland gpib_user.h ensuring backward
compatibility for application programmes.

Rename the file and change the references to it.

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250418093111.8820-3-dpenkler@gmail.com


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