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>
(cherry picked from commit 669dca3)
Cc: stable@vger.kernel.org

Author: superm1

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c

@@ -1734,12 +1734,13 @@ static bool retrieve_link_cap(struct dc_link *link)
 	}
 
 	dpcd_set_source_specific_data(link);
-	/* Sink may need to configure internals based on vendor, so allow some
-	 * time before proceeding with possibly vendor specific transactions
-	 */
-	msleep(post_oui_delay);
 
 	for (i = 0; i < read_dpcd_retry_cnt; i++) {
+		/*
+		 * Sink may need to configure internals based on vendor, so allow some
+		 * time before proceeding with possibly vendor specific transactions
+		 */
+		msleep(post_oui_delay);
 		status = core_link_read_dpcd(
 				link,
 				DP_DPCD_REV,