test(hw, adrv9371): poll for JESD relock after ensm_mode=radio_on

Empirical evidence from CI run 24722162544: ``echo radio_on``
successfully latches ``ensm_mode`` but bounces JESD204 RX (Mykonos
re-runs part of ARM init on first radio_on, same symptom as
``profile_config`` write).  A 1-second sleep catches the link
mid-retrain, so the existing ``assert_jesd_links_data`` call
fails.

Poll for both RX + TX to return to DATA, up to 30 s, before
re-verifying — same pattern the reverted commit 5222208 tried for
``profile_config``.  For ENSM it may converge; the 30 s budget is
the empirical test.  If the link still doesn't come back the
assertion will fail with the "(up to 30 s)" suffix, pointing at a
genuinely different Mykonos behaviour rather than an undercooked
timeout.

Author: tfcollins

test/hw/test_adrv9371_zc706_hw.py

@@ -185,9 +185,24 @@ def test_adrv9371_zc706_xsa_hw(board, built_kernel_image_zynq, tmp_path):
     )
     print(f"post-write ensm_mode: {post_ensm}")
 
-    # ENSM transition should not disturb the link — the Mykonos ARM
-    # just starts streaming.  Re-verify JESD + dmesg stayed clean.
-    assert_jesd_links_data(shell, context="after ensm_mode=radio_on")
+    # Empirically the ENSM radio_on transition bounces the JESD204
+    # RX link (Mykonos re-runs ARM init as part of entering radio_on
+    # for the first time).  Poll for both links to return to DATA,
+    # up to 30 s, before re-verifying dmesg health.
+    from test.hw.hw_helpers import read_jesd_status  # noqa: PLC0415
+
+    deadline = time.time() + 30.0
+    while True:
+        time.sleep(2.0)
+        rx_status, tx_status = read_jesd_status(shell)
+        if (
+            "Link status: DATA" in rx_status
+            and "Link status: DATA" in tx_status
+        ):
+            break
+        if time.time() > deadline:
+            break
+    assert_jesd_links_data(shell, context="after ensm_mode=radio_on (up to 30 s)")
     post_ensm_dmesg = shell_out(shell, "dmesg")
     assert_no_kernel_faults(post_ensm_dmesg)
     assert_no_probe_errors(post_ensm_dmesg)