usbip: vudc: fix missing unlock on error in usbip_sockfd_store()

usbip: vudc: fix missing unlock on error in usbip_sockfd_store()

BugLink: https://bugs.launchpad.net/bugs/1929615
[ Upstream commit 1d08ed588c6a85a35a24c82eb4cf0807ec2b366a ]

Add the missing unlock before return from function usbip_sockfd_store()
in the error handling case.

Fixes: bd8b82042269 ("usbip: vudc synchronize sysfs code paths")
Reported-by: Hulk Robot <hulkci@huawei.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Link: https://lore.kernel.org/r/20210408112305.1022247-1-yebin10@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>