dtoverlays: Correct field sizes in pcie-32bit-dma

Adding the dma-ranges to the overlay missed setting the field sizes,
so the compiler rightly flagged a warning.

https://github.com/raspberrypi/linux/issues/4848



Fixes: ee6a81c8 "dtoverlay: Reduce size of PCIE IB window in pcie-32-dma overlay"

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>