drm/amdgpu/display: use msleep rather than udelay for long delays

Some architectures (e.g., ARM) throw an compilation error if the
udelay is too long.  In general udelays of longer than 2000us are
not recommended on any architecture.  Switch to msleep in these
cases.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -6935,7 +6935,7 @@ bool dpcd_write_128b_132b_sst_payload_allocation_table(
 			}
 		}
 		retries++;
-		udelay(5000);
+		msleep(5);
 	}
 
 	if (!result && retries == max_retries) {
@@ -6987,7 +6987,7 @@ bool dpcd_poll_for_allocation_change_trigger(struct dc_link *link)
 			break;
 		}
 
-		udelay(5000);
+		msleep(5);
 	}
 
 	if (result == ACT_FAILED) {