crypto: caam - Fix null dereference at error path

commit b85149f6 upstream.

caam_remove already removes the debugfs entry, so we need to remove the one
immediately before calling caam_remove.

This fix a NULL dereference at error paths is caam_probe fail.

Fixes: 67c2315d ("crypto: caam - add Queue Interface (QI) backend support")

Tested-by: Ryan Harkin <ryan.harkin@linaro.org>
Cc: "Horia Geantă" <horia.geanta@nxp.com>
Cc: Aymen Sghaier <aymen.sghaier@nxp.com>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Cc: <stable@vger.kernel.org> # 4.12+
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>