PCI: al: Select CONFIG_PCI_ECAM

Compile-testing this driver without ECAM support results in a link failure:

  ld.lld: error: undefined symbol: pci_ecam_map_bus
  >>> referenced by pcie-al.c
  >>>               pci/controller/dwc/pcie-al.o:(al_pcie_map_bus) in archive drivers/built-in.a

Select CONFIG_ECAM like the other drivers do.

Link: https://lore.kernel.org/r/20210308152501.2135937-1-arnd@kernel.org


Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>