arm/dt: 9625: Set USB ITC value to 16

By default the ITC will be set to 0, which correspond to 125 usecs. This
change sets the ITC value to 16 (2 msecs). This will decrease the
number of interrupts which will offload the CPU, and allow higher
throughput.

Change-Id: I77d7b54313a4bb93f60fa3895e2b21f6c3fee7cf
Signed-off-by: Amit Blay <ablay@codeaurora.org>