PCI/AER: Simplify AER_RECOVER_RING_SIZE definition

ACPI Platform Error Interfaces (APEI) convey error information to the OS.
If the APEI GHES driver receives information about PCI errors, it queues it
in aer_recover_ring for processing by the PCI AER code.

AER_RECOVER_RING_SIZE is the size of the aer_recover_ring FIFO and is
arbitrary, with no direct connection to hardware.

AER_RECOVER_RING_ORDER was only used to compute AER_RECOVER_RING_SIZE.
Remove it and define AER_RECOVER_RING_SIZE directly.  No functional change
intended.

Link: https://lore.kernel.org/r/20230824193712.542167-7-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>