Revert "pci: Scale MAX_PCI_REGIONS based on CONFIG_NR_DRAM_BANKS"

Revert "pci: Scale MAX_PCI_REGIONS based on CONFIG_NR_DRAM_BANKS"

This reverts commit aec4298ccb337106fd0115b91d846a022fdf301d.

Unfortunately this has a dramatic impact on the pre-relocation memory
used on x86 platforms (increasing it by 2KB) since it increases the
overhead for each PCI device from 220 bytes to 412 bytes.

The offending line is in UCLASS_DRIVER(pci):

	.per_device_auto_alloc_size = sizeof(struct pci_controller),

This means that all PCI devices have the controller struct associated
with them. The solution is to move the regions[] member out of the array,
makes its size dynamic, or split UCLASS_PCI into controllers and
non-controllers, as the comment suggests.

For now, revert the commit to get things running again.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>