[why]
Currently the amdgpu DM psr configuration parameters are hardcoded
before feeding into the DC helper to setup PSR. We would define a
helper which is to calculate parts of the psr config fields to
avoid hard-coding.

[how]
To make helper shareable, declare and define the helper in the
module_helper, to set/update below fields:
- psr remote buffer setup time
- sdp tx line number deadline
- line time in us
- su_y_granularity
- su_granularity_required
- psr_frame_capture_indication_req
- psr_exit_link_training_required

add another helper to check given the stream context, if there is
only one stream and the output is eDP panel connected.

changes in v2:
------------------
- add detailed comment for how psr setup time is calculated as per
  eDP 1.5 spec

Cc: Chandan Vurdigerenataraj <chandan.vurdigerenataraj@amd.com>
Signed-off-by: David Zhang <dingchen.zhang@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>