drm/exynos: mipi-dsi: consider non-continuous clock mode

This patch adds non-continuous clock mode support

Clock mode on Clock Lane is continuous clock by default.
So if we want to transmit data in non-continuous clock mode
to reduce power consumption, then host driver should set
DSIM_CLKLANE_STOP bit. In this case, host controller turns off
HS clock between high speed transmissions.

For this, this patch adds a new bit, DSIM_CLKLANE_STOP, and makes
the host driver sets this bit only in case that dsi->mode_flags has
MIPI_DSI_CLOCK_NON_CONTINUOUS flag.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>