configs/qemu: update infos for latest qemu version

board/qemu/aarch64-virt/readme.txt

board/qemu/arm-nuri/readme.txt

board/qemu/arm-versatile/readme.txt

board/qemu/arm-vexpress/readme.txt

board/qemu/microblazebe-mmu/readme.txt

board/qemu/microblazeel-mmu/readme.txt

board/qemu/mips-malta/readme.txt

board/qemu/mips64-malta/readme.txt

board/qemu/mips64el-malta/readme.txt

board/qemu/mipsel-malta/readme.txt

board/qemu/ppc-g3beige/readme.txt

board/qemu/ppc-mpc8544ds/readme.txt

board/qemu/ppc-virtex-ml507/readme.txt

board/qemu/ppc64-pseries/readme.txt

board/qemu/sh4-r2d/readme.txt

board/qemu/sparc-ss10/readme.txt

board/qemu/x86/readme.txt

board/qemu/x86_64/readme.txt

board/qemu/xtensa-lx60/readme.txt