drm/msm: Display Fixes for v6.1

Hi Rob

This is the display side fixes list for 6.1. Here is the description of the changes:

1. Fix for avoiding a double-disable from DRM leading to an unclocked access in DP driver when usermode crashes. This fix implements an atomic_check helper for DP driver and rejects commits if cable is not connected.
2. Fix the return type of mdp4_lvds_connector_mode_valid from int to enum drm_mode_status
3. Set of fixes in DP driver which address foll issues: a) Reset the priv->num_bridges to ensure stale pointers to deallocated structures are not accessed b) Add protection for num_bridges to not exceed the size of the num_bridges array for DSI, DP and HDMI c) Change the device-managed lifetime of the IRQ, aux-bus and bridge for DP and the IRQ for HDMI to the DRM device so that it is released when bind
   fails. Otherwise it will remain requested and the next bind attempt fails when requesting the IRQ a second time. This can easily happen during probe
   defer cases
4. Clear the DP_DOWNSPREAD_CTRL register before starting link training for DP. Otherwise, for some dongles it retains a stale value which could incorrectly set the MSA_TIMING_PAR_IGNORE_EN bit making the dongles not to work correctly as they could misinterpret the MSA parameters.

Thanks

Abhinav