uio devicetree fixes

from http://fpgacpu.wordpress.com/2013/05/28/how-to-design-and-access-a-memory-mapped-device-part-two/
dts geopebble: Correct ethernet IRQ #
geopebble spi: Correct returned length
dts geopebble: Remove unneeded spi device #address-cells and #size-cells feilds
dts geopebble: Add early template for wifi IRQ & SD-card