ar71xx: add lzma loader

target/linux/ar71xx/image/lzma-loader/Makefile

target/linux/ar71xx/image/lzma-loader/src/LzmaDecode.c

target/linux/ar71xx/image/lzma-loader/src/LzmaDecode.h

target/linux/ar71xx/image/lzma-loader/src/LzmaTypes.h

target/linux/ar71xx/image/lzma-loader/src/Makefile

target/linux/ar71xx/image/lzma-loader/src/board.c

target/linux/ar71xx/image/lzma-loader/src/cache.c

target/linux/ar71xx/image/lzma-loader/src/cache.h

target/linux/ar71xx/image/lzma-loader/src/cacheops.h

target/linux/ar71xx/image/lzma-loader/src/config.h

target/linux/ar71xx/image/lzma-loader/src/cp0regdef.h

target/linux/ar71xx/image/lzma-loader/src/head.S

target/linux/ar71xx/image/lzma-loader/src/loader.c

target/linux/ar71xx/image/lzma-loader/src/loader.lds

target/linux/ar71xx/image/lzma-loader/src/lzma-data.lds

target/linux/ar71xx/image/lzma-loader/src/printf.c

target/linux/ar71xx/image/lzma-loader/src/printf.h