disp: msm: sde: correct num_datapath during PM resume with CWB

In PM resume with CWB concurrency usecase, crtc pointer in
conn->state is NULL since drm_mode_config_reset operation is
performed on pm_resume. This change relies on conn_mask in
new_crtc_state for primary connector retrieval and also adds
get_num_lm_from_mode callback to DSI for LM count retrieval
from dsi panel topology. Existing get_mode_info api cannot
retrieve the topology info because mode->priv_info is NULL.
This occurs as WB encoder is added in the drm encoder_list
before primary encoder, introduced as part of commit d28ebf05
("disp: msm: sde: populate WB display encoder list before dsi").

Change-Id: I55358fd88ab778bd81475cf3628be13335de1cb5
Signed-off-by: Jayaprakash Madisetty <jmadiset@codeaurora.org>