kernel: fix DMA error when BCM4331 is connected to BCM4706

The BCM4331 supports a PCIe max request size of 512 bytes and uses 
that, but the PCIe controller in the BCM4706 just supports 128 Bytes 
and that causes a DMA error for packages bigger than 126 bytes. This 
fixes the problem by setting the BCM4331 also to 128 Bytes.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>


git-svn-id: svn://svn.openwrt.org/openwrt@37709 3c298f89-4303-0410-b956-a3cf2f4a3e73