buildroot

boot/uboot: compute CRC on SPLs for Altera SoC FPGA

Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
[Thomas: add Altera in the option name and description, drop reference
to Go being needed and to Maxime Hadjinlian's version of mkpimage
since a C version is now used.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>