omapfb: fix spelling mistake "propert" -> "property"

There is a spelling mistake in a pr_err message. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200805102805.15353-1-colin.king@canonical.com