ehci-hcd: fix memory leak in lowlevel init

usb_lowlevel_init() allocates a new periodic_list each time it is invoked,
without freeing the original list. Since it is initialized later on in the code,
just reuse the first-allocated list in future invocations of usb_lowlevel_init.

Cc: Marek Vasut <marex@denx.de>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>

drivers/usb/host/ehci-hcd.c

@@ -945,7 +945,9 @@ int usb_lowlevel_init(int index, void **controller)
 	 *         Split Transactions will be spread across microframes using
 	 *         S-mask and C-mask.
 	 */
+	if (ehcic[index].periodic_list == NULL)
 		ehcic[index].periodic_list = memalign(4096, 1024 * 4);
+
 	if (!ehcic[index].periodic_list)
 		return -ENOMEM;
 	for (i = 0; i < 1024; i++) {