bnxt_en: Skip firmware fatal error recovery if chip is not accessible

Driver starts firmware fatal error recovery by detecting
heartbeat failure or fw reset count register changing.  But
these checks are not reliable if the device is not accessible.
This can happen while DPC (Downstream Port containment) is in
progress.  Skip firmware fatal recovery if pci_device_is_present()
returns false.

Fixes: acfb50e4 ("bnxt_en: Add FW fatal devlink_health_reporter.")
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Vikas Gupta <vikas.gupta@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>