PCI/AER: Remove redundant dev->aer_cap checks

pcie_aer_get_firmware_first() checks dev->aer_cap, so we can remove
redundant dev->aer_cap checks in the callers.

Link: https://lore.kernel.org/r/d5ccc7a060ec9cdc234bdae7df8a0a4410f13f42.1590534843.git.sathyanarayanan.kuppuswamy@linux.intel.com


Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>