ARM: mach-imx: clk-imx51-imx53: Fix 'spdif1_pred' clock registration

Since commit beb2d1c1 (ARM i.MX5: Add S/PDIF clocks), the following clock
error appears on mx51:

TrustZone Interrupt Controller (TZIC) initialized
i.MX51 clk 180: register failed with -17
i.MX5 clk 180: register failed with -17
sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 178956ms
CPU identified as i.MX51, silicon rev 3.0
...

Clock 180 corresponds to 'spdif1_podf' and this clock is getting registered
twice.

Fix it, by properly registering the 'spdif1_pred' clock, which should not
reference 'spdif1_podf'.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>