Like msm8916-samsung-a3u-eur, the Grand Prime uses a Zinitix BT541 touchscreen. Add it together with the necessary fixed-regulator to the device tree. Most of the Galaxy Grand Prime use backlight drivers controlled with PWM signal. To simplify the description, add the backlight with the necessary clk-pwm to the common dtsi. --- v2: Add &touchscreen. Keep i2c5 enabled v3: Drop linux,keycodes. Add PWM backlight
