staging: gpib: fix Makefiles

staging: gpib: fix Makefiles

Having gpib drivers built-in rather than as loadable modules causes
link failure because the drivers are never actually built:

arm-linux-gnueabi-ld: drivers/staging/gpib/fmh_gpib/fmh_gpib.o: in function `fmh_gpib_t1_delay':
fmh_gpib.c:(.text+0x3b0): undefined reference to `nec7210_t1_delay'
arm-linux-gnueabi-ld: drivers/staging/gpib/fmh_gpib/fmh_gpib.o: in function `fmh_gpib_serial_poll_status':
fmh_gpib.c:(.text+0x418): undefined reference to `nec7210_serial_poll_status'
arm-linux-gnueabi-ld: drivers/staging/gpib/fmh_gpib/fmh_gpib.o: in function `fmh_gpib_secondary_address':
fmh_gpib.c:(.text+0x57c): undefined reference to `nec7210_secondary_address'
arm-linux-gnueabi-ld: drivers/staging/gpib/fmh_gpib/fmh_gpib.o: in function `fmh_gpib_primary_address':
fmh_gpib.c:(.text+0x5ac): undefined reference to `nec7210_primary_address'

Change this to use the correct Makefile syntax, setting either obj-m or obj-y.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20241212154245.1411411-2-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>