staging: gpib: refer to correct config symbol in tnt4882 Makefile

Commit 79d2e19 ("staging: gpib: fix Makefiles") uses the corresponding
config symbols to let Makefiles include the driver sources appropriately in
the kernel build.

Unfortunately, the Makefile in the tnt4882 directory refers to the
non-existing config GPIB_TNT4882. The actual config name for this driver is
GPIB_NI_PCI_ISA, as can be observed in the gpib Makefile.

Probably, this is caused by the subtle differences between the config
names, directory names and file names in ./drivers/staging/gpib/, where
often config names and directory names are identical or at least close in
naming, but in this case, it is not.

Change the reference in the tnt4882 Makefile from the non-existing config
GPIB_TNT4882 to the existing config GPIB_NI_PCI_ISA.

Fixes: 79d2e19 ("staging: gpib: fix Makefiles")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Link: https://lore.kernel.org/r/20250107135032.34424-1-lukas.bulwahn@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gpib/tnt4882/Makefile

@@ -1,5 +1,5 @@
 ccflags-$(CONFIG_GPIB_PCMCIA) := -DGPIB_PCMCIA
-obj-$(CONFIG_GPIB_TNT4882) += tnt4882.o
+obj-$(CONFIG_GPIB_NI_PCI_ISA) += tnt4882.o
 
 tnt4882-objs := tnt4882_gpib.o mite.o