usbip: usbip_host: fix stub_dev lock context imbalance regression

Fix the following sparse context imbalance regression introduced in
a patch that fixed sleeping function called from invalid context bug.

kbuild test robot reported on:

tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git

  usb-linus

Regressions in current branch:

drivers/usb/usbip/stub_dev.c:399:9: sparse: sparse: context imbalance in 'stub_probe' - different lock contexts for basic block
drivers/usb/usbip/stub_dev.c:418:13: sparse: sparse: context imbalance in 'stub_disconnect' - different lock contexts for basic block
drivers/usb/usbip/stub_dev.c:464:1-10: second lock on line 476

Error ids grouped by kconfigs:

recent_errors
├── i386-allmodconfig
│   └── drivers-usb-usbip-stub_dev.c:second-lock-on-line
├── x86_64-allmodconfig
│   ├── drivers-usb-usbip-stub_dev.c:sparse:sparse:context-imbalance-in-stub_disconnect-different-lock-contexts-for-basic-block
│   └── drivers-usb-usbip-stub_dev.c:sparse:sparse:context-imbalance-in-stub_probe-different-lock-contexts-for-basic-block
└── x86_64-allyesconfig
    └── drivers-usb-usbip-stub_dev.c:second-lock-on-line

This is a real problem in an error leg where spin_lock() is called on an
already held lock.

Fix the imbalance in stub_probe() and stub_disconnect().

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Fixes: 0c9e8b3c ("usbip: usbip_host: fix BUG: sleeping function called from invalid context")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>