IOMUX: Fix stopping unused dropped consoles

iomux_match_device() returns -ENOENT instead of the end index, which means
console_stop() is never called at the moment for unused consoles.

This prevents e.g. f_acm from releasing the USB gadget interface when
removing it from stdio/stderr/stdin.

Fixes: b672c1619b ("IOMUX: Split out iomux_match_device() helper")
Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

common/iomux.c

@@ -131,7 +131,7 @@ int iomux_doenv(const int console, const char *arg)
 	/* Stop dropped consoles */
 	for (i = 0; i < repeat; i++) {
 		j = iomux_match_device(cons_set, cs_idx, old_set[i]);
-		if (j == cs_idx)
+		if (j == -ENOENT)
 			console_stop(console, old_set[i]);
 	}