initialize timer in bsp

With new timer algorithm, timer should be initialized during startup. So
add them to the bsps. Use these commands to get which bsp is missing
calling the function:

    % git grep rt_system_timer_init bsp|sed -n 's|bsp/\([^/]*\).*|\1|p' | sort | uniq > have_tm_init
    % ls -1 bsp |sed -n 's|\([^/]*\).*|\1|p' | sort > all_bsp
    % comm -3 all_bsp have_tm_init
    beaglebone
    lpc176x
    lpc178x
    ls1bdev
    mb9bf506r
    stm32f10x
    xplorer4330
Merge pull request #182 from grissiom/fix-timer-init

initialize timer in bsp