staging: mt7621-pci: avoid to set 'iomem_resource' addresses

Setting up kernel resource 'iomem_resource' for PCI with
addresses parsed from device tree gots into a conflict within
the usb xhci driver:

xhci-mtk 1e1c0000.xhci: can't request region for resource [mem 0x1e1c0000-0x1e1c0fff]
xhci-mtk: probe of 1e1c0000.xhci failed with error -16

Don't assign it and maintain the default addresses for this
resource seems to fix the problem. Checking legacy driver it
is being only  setting the 'ioport_resource'.

Fixes: 09dd629e ("staging: mt7621-pci: fix io space and properly set resource limits")
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200322072128.4454-1-sergio.paracuellos@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pci/pci-mt7621.c

@@ -679,8 +679,6 @@ static int mt7621_pci_probe(struct platform_device *pdev)
 	}
 
 	/* set resources limits */
-	iomem_resource.start = pcie->mem.start;
-	iomem_resource.end = pcie->mem.end;
 	ioport_resource.start = pcie->io.start;
 	ioport_resource.end = pcie->io.end;