staging: gpib: Workaround for ppc build failure

Make GPIB_FMH depend on !PPC

Reported_by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/all/20241015165538.634707e5@canb.auug.org.au/
Link: https://lore.kernel.org/r/20241204134736.6660-1-dpenkler@gmail.com


Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>