efi/cper: Remove unnecessary aer.h include

<linux/aer.h> is unused, so remove it.

Link: https://lore.kernel.org/r/20230307203356.882479-1-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>