mlxsw: spectrum: Fix error path in mlxsw_sp_module_init()

[ Upstream commit 28fe79000e9b0a6f99959869947f1ca305f14599 ]

In case of sp2 pci driver registration fail, fix the error path to
start with sp1 pci driver unregister.

Fixes: c3ab4354 ("mlxsw: spectrum: Extend to support Spectrum-2 ASIC")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>