dt-bindings/interrupt-controller: pdc: fix example to match actual bindings

The PDC map should use the GIC SPI port and not the vector. GIC
internally adds 32 to SPI hwirq numbers.

Change-Id: Ifcf3b9fc352d0e19b2b54b394beac8f7502c7707
Fixes: 1ae8862e ("dt-bindings/interrupt-controller: pdc: Describe PDC device binding")
Signed-off-by: Lina Iyer <ilina@codeaurora.org>