staging: vme: Move vme_user to staging KConfig

staging: vme: Move vme_user to staging KConfig

Currently, the VME_USER driver is in the staging tree Kconfig, unlike
other VME drivers already moved to the main portions of the kernel tree.
Its configuration is, however, nested into the VME_BUS config option,
which might be misleading.

Since the staging tree "[...] is used to hold stand-alone drivers and
filesystem that are not ready to be merged into the main portion of the
Linux kernel tree [...]"(from
https://lore.kernel.org/all/20090320172502.GA14647@kroah.com/T/),
staging drivers should appear nested into the Main Menu -> Device
Drivers -> Staging Drivers to make sure the user don't pick it without
being fully aware of its staging status as it could be the case in
Menu -> Device Drivers -> VME bridge support (the current location).

With this change menuconfig users will clearly know this is not a driver
in the main portion of the kernel tree and decide whether to build it or
not with that clearly in mind.

This change goes into the same direction of commit
<4b4cdf3979c32fa3d042d150f49449c74d048553> ("STAGING: Move staging
drivers back to staging-specific menu")

Signed-off-by: Bruno Moreira-Guedes <codeagain@codeagain.dev>
Link: https://lore.kernel.org/r/f6e6d1d2b02385f11848022f154007ef191181c1.1650544175.git.codeagain@codeagain.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>