drm/bridge: adv7511: fix spelling of driver name in Kconfig

Could perhaps prevent some confusion.

Signed-off-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180426213644.29318-1-peda@axentia.se