Current implementation of write_config() is broken for PCI_SIZE_8 or
PCI_SIZE_16 as it always uses writel(), which means that write operation
is always 32-bit, so upper 24 bits for PCI_SIZE_8 and upper 16 bits for
PCI_SIZE_16 are cleared.

Fix this by using writeb() and writew(), respectively.
Signed-off-by: NPali Rohár <pali@kernel.org>
Reviewed-by: NMarek Behún <marek.behun@nic.cz>
Reviewed-by: NStefan Roese <sr@denx.de>