drm/kmb: fix spelling mistakes in drm_info and drm_dbg messages

There are two spelling mistakes of the word sync in drm_info
and drm_dbg messages. Fix these.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109111225.1485190-1-colin.king@canonical.com