ci: driver build fails after makefile relaxed to easier use on multiple architectures.
When KDIR is specified then new version does not enforce ARM target build because it complicates MIPS and native builds. But when the Linux kernel build directory does not contain GNUmakefile trick to setup ARCH and CROSS_COMPILE, then plain make with KDIR fails after relaxation. Specification of the ARM target explicitly in CI command is required now.