firmware: google memconsole: Remove useless submenu in Kconfig

This patch removes the "Google Firmware Drivers" menu containing a
menuconfig entry with the exact same name. The menuconfig is now
directly under the "Firmware Drivers" entry.

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>