arm: socfpga: misc: Add support for printing FPGA type

Add code which uses the new functions for obtaining FPGA ID from
the scan manager. This new code prints the FPGA model attached to
the SoCFPGA during boot and sets environment variable "fpgatype",
which can be used to determine the FPGA model in U-Boot scripts.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Marek Vasut <marex@denx.de>