VME: restore bus_remove function causing incomplete module unload

Commit 050c3d52 ("vme: make core
vme support explicitly non-modular") dropped the remove function
because it appeared as if it was for removal of the bus, which is
not supported.

However, vme_bus_remove() is called when a VME device is removed
from the bus and not when the bus is removed; as it calls the VME
device driver's cleanup function.  Without this function, the
remove() in the VME device driver is never called and VME device
drivers cannot be reloaded again.

Here we restore the remove function that was deleted in that
commit, and the reference to the function in the bus structure.

Fixes: 050c3d52 ("vme: make core vme support explicitly non-modular")
Cc: Manohar Vanga <manohar.vanga@gmail.com>
Acked-by: Martyn Welch <martyn@welchs.me.uk>
Cc: devel@driverdev.osuosl.org
Signed-off-by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: stable <stable@vger.kernel.org> # 4.9
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>