Add RISC-V 32-bit defconfig for QEMU virt machine. Tested with QEMU 2.12.1 Signed-off-by: Mark Corbin <mark.corbin@embecosm.com> Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com> [Thomas: regenerate .gitlab-ci.yml, update DEVELOPERS file] Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>