s5j/pwm: rework pwm driver

s5j/pwm: rework pwm driver

fix prefix for s5j, functions are named as s5j_pwm_xxx. SFR access uses
getreg/putreg. sidk_s5jt200 board initializes pwm channels accordingly
for board definition. It has 6 PWM output and 3 s8300 driver exsited on
sidk s5jt200 evaludation board.

pwm functions except s5j_pwminitialize names with staic and not appears
lower half and upper half.

FAR struct pwm_lowerhalf_s *foo;
foo->ops->start() is allowed to access PWM functionalities.

Change-Id: I120284b114f9994ec96e100809975b0e17823fa7
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>