powerpc/85xx: Add support for the "socrates" board (MPC8544).

Supported are Ethernet, serial console, I2C, I2C-based RTC and
temperature sensors, NOR and NAND flash, PCI, USB, CAN and Lime
display controller.

The multiplexing of FPGA interrupts onto PowerPC interrupt lines is
supported through our own fpga_pic interrupt controller driver.

For example the SJA1000 controller is level low sensitive connected to
fpga_pic line 2 and is routed to the second (of three) irq lines to
the CPU:

    can@3,100 {
            compatible = "philips,sja1000";
            reg = <3 0x100 0x80>;
            interrupts = <2 2>;
            interrupts = <2 8 1>;   // number, type, routing
            interrupt-parent = <&fpga_pic>;
    };

Signed-off-by: Sergei Poselenov <sposelenov@emcraft.com>
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Dmitry Rakhchev <rda@emcraft.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>