ntb: intel: Fix memleak in intel_ntb_pci_probe

The default error branch of a series of pdev_is_gen calls
should free ndev just like what we've done in these calls.

Fixes: 26bfe3d0

 ("ntb: intel: Add Icelake (gen4) support for Intel NTB")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>