mei: fix vsc dependency

mei: fix vsc dependency

CONFIG_INTEL_MEI_VSC_HW can be set to built-in even with CONFIG_MEI=m,
but then the driver is not built because Kbuild never enters the
drivers/misc/mei directory for built-in files, leading to a link
failure:

ERROR: modpost: "vsc_tp_reset" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_init" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_xfer" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_need_read" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_intr_enable" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_intr_synchronize" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_intr_disable" [drivers/misc/mei/mei-vsc.ko] undefined!
ERROR: modpost: "vsc_tp_register_event_cb" [drivers/misc/mei/mei-vsc.ko] undefined!

Add an explicit dependency on CONFIG_MEI that was apparently missing,
to ensure the VSC_HW driver cannot be built-in with MEI itself being
a loadable module.

Fixes: 566f5ca97680 ("mei: Add transport driver for IVSC device")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Wentong Wu <wentong.wu@intel.com>
Link: https://lore.kernel.org/r/20231214183946.109124-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>