bnxt_en: fix error return code in bnxt_init_board()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: c0c050c5 ("bnxt_en: New Broadcom ethernet driver.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Link: https://lore.kernel.org/r/1605792621-6268-1-git-send-email-zhangchangzhong@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>