alx: Fix an error handling path in 'alx_probe()'

[ Upstream commit 33e381448cf7a05d76ac0b47d4a6531ecd0e5c53 ]

If an error occurs after a 'pci_enable_pcie_error_reporting()' call, it
must be undone by a corresponding 'pci_disable_pcie_error_reporting()'
call, as already done in the remove function.

Fixes: ab69bde6 ("alx: add a simple AR816x/AR817x device driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>