arm: ls1021a: Add timer_init() in board_init_f for SPL

arm: ls1021a: Add timer_init() in board_init_f for SPL

I2C is used to access DDR SPD in the DDR initialization for SPL. In
i2c_write process, get_timer() will be called. In board_init_f for SPL,
timer_init() is not called before. The system counter is not enabled and
the counter frequency is not set to 12.5MHz in SPL. The parameters for
do_div() are zero too.

It could not be found until CONFIG_USE_PRIVATE_LIBGCC is enabled in
default. When CONFIG_USE_PRIVATE_LIBGCC is enabled, U-Boot will use its
own set of libgcc functions. As the parameters for do_div() are zero,
__div0 will be called. Then the processor will stay in an endless loop
after calling hang().

This patch will add timer_init() in board_init_f for SPL and fix a
series of issues it caused.

Signed-off-by: Alison Wang <alison.wang@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>