drm/bridge/sii8620: fix MSC message removal

Messages queue can be cleaned up by message callbacks, to avoid repeated
removal of current message it should be removed from the queue before
calling these callbacks.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1485935272-17337-12-git-send-email-a.hajda@samsung.com