net: ipa: balance runtime PM reference on remove error

ipa_remove() takes a runtime PM reference before accessing IPA hardware
during teardown. If a concurrent modem start or stop keeps
ipa_modem_stop() busy across both attempts, the callback intentionally
returns without releasing the remaining resources because proceeding
with teardown could crash. That return also skips the matching
pm_runtime_put_noidle(), leaving the callback's usage-count reference
held.

Drop only this runtime PM reference before returning.
pm_runtime_put_noidle() does not request an idle transition, so the
hardware and resources retained on this exceptional path remain
untouched while the usage count stays balanced.

This issue was found by a static analysis checker and confirmed by
manual source review.

Fixes: 923a6b6984 ("net: ipa: get clock in ipa_probe()")
Signed-off-by: Ruoyu Wang <[email protected]>
Reviewed-by: Alex Elder <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

drivers/net/ipa/ipa_main.c

@@ -972,12 +972,12 @@ static void ipa_remove(struct platform_device *pdev)
 		}
 		if (ret) {
 			/*
-			 * Not cleaning up here properly might also yield a
-			 * crash later on. As the device is still unregistered
-			 * in this case, this might even yield a crash later on.
+			 * Continuing teardown after failing to stop the modem
+			 * could crash, so leave the remaining resources allocated.
 			 */
 			dev_err(dev, "Failed to stop modem (%pe), leaking resources\n",
 				ERR_PTR(ret));
+			pm_runtime_put_noidle(dev);
 			return;
 		}