drm/bridge/synopsys: dsi: add support for non-continuous HS clock

[ Upstream commit c6d94e37bdbb6dfe7e581e937a915ab58399b8a5 ]

Current code enables the HS clock when video mode is started or to
send out a HS command, and disables the HS clock to send out a LP
command. This is not what DSI spec specify.

Enable HS clock either in command and in video mode.
Set automatic HS clock management for panels and devices that
support non-continuous HS clock.

Signed-off-by: Antonio Borneo <antonio.borneo@st.com>
Tested-by: Philippe Cornu <philippe.cornu@st.com>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701194234.18123-1-yannick.fertre@st.com


Signed-off-by: Sasha Levin <sashal@kernel.org>