make mips_machine stuff available for other MIPS targets

target/linux/adm5120/router_be/config-2.6.26

target/linux/adm5120/router_be/config-2.6.27

target/linux/adm5120/router_le/config-2.6.26

target/linux/adm5120/router_le/config-2.6.27

target/linux/ar7/config-2.6.26

target/linux/ar71xx/Makefile

target/linux/atheros/config-2.6.26

target/linux/atheros/config-2.6.27

target/linux/au1000/config-2.6.27

target/linux/brcm63xx/config-2.6.27

...c-2.6/patches-2.6.26/020-mips_multi_machine_support.patch

...c-2.6/patches-2.6.27/020-mips_multi_machine_support.patch

target/linux/ifxmips/config-2.6.26

target/linux/rb532/config-2.6.27

target/linux/sibyte/config-default