drm/amd/display: Move sleep into each retry for retrieve_link_cap()

drm/amd/display: Move sleep into each retry for retrieve_link_cap()

[Why]
When a monitor is booting it's possible that it isn't ready to retrieve
link caps and this can lead to an EDID read failure:

```
[drm:retrieve_link_cap [amdgpu]] *ERROR* retrieve_link_cap: Read receiver caps dpcd data failed.
amdgpu 0000:c5:00.0: [drm] *ERROR* No EDID read.
```

[How]
Rather than msleep once and try a few times, msleep each time.  Should
be no changes for existing working monitors, but should correct reading
caps on a monitor that is slow to boot.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4672
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>