ANDROID: drm: dsi: add two DSI mode flags for BLLP

Add two dsi mode flag namely MIPI_DSI_MODE_VIDEO_BLLP
and MIPI_DSI_MODE_VIDEO_EOF_BLLP. MIPI_DSI_MODE_VIDEO_BLLP
flag is used when DSI is allowed to enter low power stop mode
during BLLP period, and MIPI_DSI_MODE_VIDEO_EOF_BLLP
is used when DSI is allowed to enter low power stop  mode in
the BLLP area of the last line of a frame.

Signed-off-by: Shashank Babu Chinta Venkata <sbchin@codeaurora.org>
Bug: 139653858
Change-Id: I54c1d0cc7a87d23054b82cfa975117f0590ca2d3
Signed-off-by: Matthias Maennich <maennich@google.com>