ksmbd: fix uninitialized symbol 'share' in smb2_tree_connect()

Fix uninitialized symbol 'share' in smb2_tree_connect().

Fixes: e9d8c2f9 ("ksmbd: add continuous availability share parameter")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>