[CIFS] fix small memory leak in an error path in new posix mkdir

There is a small memory leak in fs/cifs/inode.c::cifs_mkdir().
Storage for 'pInfo' is allocated with kzalloc(), but if the call
to CIFSPOSIXCreate(...) happens to return 0 and pInfo->Type == -1,
then we'll jump to the 'mkdir_get_info' label without freeing the
storage allocated for 'pInfo'.
This patch adds a kfree() call to free the storage just before
jumping to the label, thus getting rid of the leak.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>