tty: serial: Fix refcount leak bug in ucc_uart.c

stable inclusion
from stable-v5.10.138
commit 81939c4fbc2d5c754d0f1c1f05149d4b70d751ed
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60QFD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=81939c4fbc2d5c754d0f1c1f05149d4b70d751ed

--------------------------------

[ Upstream commit d24d7bb2 ]

In soc_info(), of_find_node_by_type() will return a node pointer
with refcount incremented. We should use of_node_put() when it is
not used anymore.
Acked-by: NTimur Tabi <timur@kernel.org>
Signed-off-by: NLiang He <windhl@126.com>
Link: https://lore.kernel.org/r/20220618060850.4058525-1-windhl@126.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/tty/serial/ucc_uart.c

@@ -1137,6 +1137,8 @@ static unsigned int soc_info(unsigned int *rev_h, unsigned int *rev_l)
 		/* No compatible property, so try the name. */
 		soc_string = np->name;
 
+	of_node_put(np);
+
 	/* Extract the SOC number from the "PowerPC," string */
 	if ((sscanf(soc_string, "PowerPC,%u", &soc) != 1) || !soc)
 		return 0;