misc: Add Lattice ECP3 FPGA configuration via SPI

This patch adds support for bitstream configuration (programming /
loading) of the Lattice ECP3 FPGA's via the SPI bus.

Here an example on my custom MPC5200 based board:

$ echo 1 > /sys/class/firmware/spi0.0/loading
$ cat fpga_a4m2k.bit > /sys/class/firmware/spi0.0/data
$ echo 0 > /sys/class/firmware/spi0.0/loading

leads to these messages:

lattice-ecp3 spi0.0: FPGA Lattice ECP3-35 detected
lattice-ecp3 spi0.0: Configuring the FPGA...
lattice-ecp3 spi0.0: FPGA succesfully configured!

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Ming Lei <ming.lei@canonical.com>
Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/Makefile

@@ -51,3 +51,4 @@ obj-$(CONFIG_ALTERA_STAPL)	+=altera-stapl/
 obj-$(CONFIG_INTEL_MEI)		+= mei/
 obj-$(CONFIG_MAX8997_MUIC)	+= max8997-muic.o
 obj-$(CONFIG_VMWARE_VMCI)	+= vmw_vmci/
+obj-$(CONFIG_LATTICE_ECP3_CONFIG)	+= lattice-ecp3-config.o