[U-Boot] [U-Boot, 4/4] rockchip: pwm: add mask for config setting

[Philipp Tomsich]

> Use mask to clear old setting before direct set the new config,
> or else there it will mess up the config when it's not the same
> with default value.
> Fixs: 3851059 rockchip: Setup default PWM flags
> 
> Signed-off-by: Kever Yang <kever.yang at rock-chips.com>
> Acked-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
> ---
> 
>  arch/arm/include/asm/arch-rockchip/pwm.h | 2 ++
>  drivers/pwm/rk_pwm.c                     | 1 +
>  2 files changed, 3 insertions(+)
> 

Reviewed-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>