clk: mxs: imx28: decrease the frequency of ref_io1 for SSP2 and SSP3

SSP0 and SSP1 use ref_io0 which has decreased frequency. Expand
the frequency fix for ref_io1 to get SSP2 and SSP3 to work.

Signed-off-by: Lauri Hintsala <lauri.hintsala@bluegiga.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>