sdl2: fix copypaste issues

This patch fixes text and mouse event processing. These functions used
'key' field of the event instead of appropriate 'text', 'motion', 'button',
or 'wheel'.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Signed-off-by: Maria Klimushenkova <maria.klimushenkova@ispras.ru>
Message-id: 20180626064017.17031.47954.stgit@pasha-VirtualBox
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>