This reverts commit 9cdf989c. The timer
has been initialized already.

It could fix the problem encountered in
https://groups.google.com/forum/?hl=en#!topic/rt-thread-cnusers/tpqZOMsIp8I

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