drm/i915/dp: use generic poll_timeout_us() instead of wait_for()

Prefer generic poll helpers over i915 custom helpers.

The functional change is losing the exponentially growing sleep of
wait_for(), which used to be 10, 20, 40, ..., 640, and 1280 us.

Use an arbitrary constant 1 ms sleep instead. The timeouts remain, being
500 ms or 1000 ms depending on the case.

Reviewed-by: Jouni Högander <[e-mail]>
Link: https://lore.kernel.org/r/83d[e-mail]
Signed-off-by: Jani Nikula <[e-mail]>

drivers/gpu/drm/i915/display/intel_dp.c

···
 	if (ret < 0)
 		return ret;
 	/* Wait for PCON to be FRL Ready */
-	wait_for(is_active = drm_dp_pcon_is_frl_ready(&intel_dp->aux) == true, TIMEOUT_FRL_READY_MS);
-
-	if (!is_active)
-		return -ETIMEDOUT;
+	ret = poll_timeout_us(is_active = drm_dp_pcon_is_frl_ready(&intel_dp->aux),
+			      is_active,
+			      1000, TIMEOUT_FRL_READY_MS * 1000, false);
+	if (ret)
+		return ret;
 
 	ret = drm_dp_pcon_frl_configure_1(&intel_dp->aux, max_frl_bw,
 					  DP_PCON_ENABLE_SEQUENTIAL_LINK);
···
 	 * Wait for FRL to be completed
 	 * Check if the HDMI Link is up and active.
 	 */
-	wait_for(is_active =
-		 intel_dp_pcon_is_frl_trained(intel_dp, max_frl_bw_mask, &frl_trained_mask),
-		 TIMEOUT_HDMI_LINK_ACTIVE_MS);
-
-	if (!is_active)
-		return -ETIMEDOUT;
+	ret = poll_timeout_us(is_active = intel_dp_pcon_is_frl_trained(intel_dp, max_frl_bw_mask, &frl_trained_mask),
+			      is_active,
+			      1000, TIMEOUT_HDMI_LINK_ACTIVE_MS * 1000, false);
+	if (ret)
+		return ret;
 
 frl_trained:
 	drm_dbg(display->drm, "FRL_TRAINED_MASK = %u\n", frl_trained_mask);