Input: max77693: Remove a read-only pwm_divisor field

Storing a predefined PWM divisor in state container structure is
meaningless. The field, after initialization, is only read so this only
obfuscates the code. Remove the field and use directly enum value.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>