drm/panel: rm67191: Remove CLOCK_NON_CONTINUOUS flag

The flag MIPI_DSI_CLOCK_NON_CONTINUOUS was wrong used in the DSI driver,
so it was added to this panel, but not necessary.
So, remove this flag since it is not needed.

Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1598626713-5595-1-git-send-email-robert.chiras@oss.nxp.com