This fix makes sure that the ISWGRP0 and ISWGRP1 registers are
correctly inited. In case those registers are not initialized,
it is not possible to access the registers synthesised in the
FPGA through the bridges. Any such access produces data abort.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>