Add an ethernet SPI chip in the OMAP4 SDP/Blaze board DTS file.

Add a fixed regulator node controlled by a GPIO line to supply
the ethernet chip.

Based on original code from Rajendra.
Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>