cns3xxx: set both MPS 'and' MRSS to 128

Fixes some DMA issues with this platform. Because this isn't currently accepted,
and can potentially disrupt other platforms (as read in commit log), I will
leave this cns3xxx specific.

Original Patch: https://patchwork.ozlabs.org/patch/600024/



Signed-off-by: Pushpal Sidhu <psidhu@gateworks.com>

SVN-Revision: 49249