arm: mvebu: a38x: serdes: Remove unused PCIe macros and functions

Remove unused PCIe functions from SerDes code. They are unused and are
duplicated either from generic PCIe code or from pci_mvebu.c.

Remove also unused PCIe macros from SerDes code. They are just obfuscated
variants of standards macros in include/pci.h or in pci_mvebu.c.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>