arm: a320: fix broken timer

timer.c used static data and are called before relocation.
Move all static variables into global_data structure. Also cleanup
timer.c from unused stubs and make it truly use 64 bit tick values.

Remove reset_timer_masked() get_timer_masked()

reference: arch/arm/cpu/arm926ejs/at91/timer.c

Based on Reinhard Meyer <u-boot@emk-elektronik.de>'s patches
5dca710a
cfff263f

Signed-off-by: Po-Yu Chuang <ratbert@faraday-tech.com>
Tested-by: Macpaul Lin <macpaul@gmail.com>