arm: a37xx: pci: Fix condition for CRS response

As stated in comment above the code, CRS response can be returned to OS
only for 4-byte PCI_VENDOR_ID config read request. So fix the code.

Fixes: 1d7ad685 ("arm: a37xx: pci: Handle propagation of CRSSVE bit from PCIe Root Port")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>