netfilter: qtaguid: Add err handle for tag cmd

In some condition, xt_qtaguid would goes into re-tagging path
with the same sk but different sockfd or socket.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++
ctrl_cmd_tag
     sockfd_lookup(e.g., sock_fd=1)
              fget(f1)
     tag f1

 ctrl_cmd_tag
      sockfd_lookup(e.g., sock_fd=2)
              fget(f2)
      retag
               fput(f1)

 ctrl_cmd_tag
      sockfd_lookup(e.g., sock_fd=3)
              fget(f3)
      retag
               fput(f1)

 ctrl_cmd_untagdd
      sockfd_lookup(e.g., sock_fd=xx)
              fput(f1)
              fput(fxx)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++

Explicitly, the first retag would trigger spinlock lockup,
and the second retag may panic because f1 has been released
during the first time re-tagging.
Or sometimes, tag -> retag -> untag -> panic, the reason is
the same.

To void the issue, we goto err path and put back the socket
ref in this call's, but not the tagged socket.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++
ctrl_cmd_tag
     sockfd_lookup(e.g., sock_fd=1)
              fget(f1)
     tag f1

 ctrl_cmd_tag
      sockfd_lookup(e.g., sock_fd=2)
              fget(f2)
      retag
	       if(f2!=f1)
      err:
               fput(f2)

 ctrl_cmd_tag
      sockfd_lookup(e.g., sock_fd=3)
              fget(f3)
      retag
	       if(f3!=f2)
      err:
               fput(f3)

 ctrl_cmd_untag
      sockfd_lookup(e.g., sock_fd=xx)
              fput(f1)
              fput(fxx)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++

Change-Id: I4ad5db2457dc55899ebbbf974dce6dc5f81293af
Signed-off-by: Hong-Mei Li <a21834@motorola.com>
Reviewed-on: http://gerrit.mot.com/626623
SLTApproved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Yi-Wei Zhao <gbjc64@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Reviewed-by: Christopher Fries <c.fries@motorola.com>
(cherry picked from commit 82760d15221e19509e85a8c43233c01741df7d4b)
Reviewed-on: http://gerrit.mot.com/629277
Reviewed-by: Upgrade Build <dbbuild@motorola.com>
SLTApproved: Upgrade Build <dbbuild@motorola.com>
Submit-Approved: Upgrade Build <dbbuild@motorola.com>
Tested-by: Upgrade Build <dbbuild@motorola.com>