Add code necessary to program the FPGA part of SoCFPGA from U-Boot
with an RBF blob. This patch also integrates the code into the
FPGA driver framework in U-Boot so it can be used via the 'fpga'
command.

Signed-off-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@altera.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Tom Rini <trini@ti.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Pavel Machek <pavel@denx.de>

V2: Move the not-CPU specific stuff into drivers/fpga/ and base
    this on the cleaned up altera FPGA support.