strip the kernel version suffix from target directories, except for brcm-2.4 (the -2.4 will be included in the board name here). CONFIG_LINUX_<ver>_<board> becomes CONFIG_TARGET_<board>, same for profiles.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@8653 3c298f89-4303-0410-b956-a3cf2f4a3e73