video: fbdev: intelfb: Use aperture size from pci_resource_len

Aperture size for i9x5 variants is determined from PCI base address.

	if (pci_resource_start(pdev, 2) & 0x08000000)
		*aperture_size = MB(128);
	...

This condition is incorrect as 128 MiB address can have the address
set as 0x?8000000 or 0x?0000000. Also the code can be simplified to just
use pci_resource_len().

The true settings of the aperture size is in the MSAC register, which
could be used instead. However the value is used only as an info message,
so it doesn't matter.

Signed-off-by: Petr Cvek <petrcvekcz@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>