bnxt_en: Remove debugfs when pci_register_driver failed

bnxt_en: Remove debugfs when pci_register_driver failed

When pci_register_driver failed, we need to remove debugfs,
which will caused a resource leak, fix it.

Resource leak logs as follows:
[   52.184456] debugfs: Directory 'bnxt_en' with parent '/' already present!

Fixes: 57aece0f11d7 ("bnxt_en: add debugfs support for DIM")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>