leds: rgb: leds-qcom-lpg: Fix calculation of best period Hi-Res PWMs

When determining the actual best period by looping through all
possible PWM configs, the resolution currently used is based on
bit shift value which is off-by-one above the possible maximum
PWM value allowed.

So subtract one from the resolution before determining the best
period so that the maximum duty cycle requested by the PWM user
won't result in a value above the maximum allowed by the selected
resolution.

Cc: [e-mail] # 6.4
Fixes: b00d2ed37617 ("leds: rgb: leds-qcom-lpg: Add support for high resolution PWM")
Signed-off-by: Abel Vesa <[e-mail]>
Reviewed-by: Sebastian Reichel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/leds/rgb/leds-qcom-lpg.c

···
 		max_res = LPG_RESOLUTION_9BIT;
 	}
 
-	min_period = div64_u64((u64)NSEC_PER_SEC * (1 << pwm_resolution_arr[0]),
+	min_period = div64_u64((u64)NSEC_PER_SEC * ((1 << pwm_resolution_arr[0]) - 1),
 			       clk_rate_arr[clk_len - 1]);
 	if (period <= min_period)
 		return -EINVAL;
···
 	 */
 
 	for (i = 0; i < pwm_resolution_count; i++) {
-		resolution = 1 << pwm_resolution_arr[i];
+		resolution = (1 << pwm_resolution_arr[i]) - 1;
 		for (clk_sel = 1; clk_sel < clk_len; clk_sel++) {
 			u64 numerator = period * clk_rate_arr[clk_sel];
 
···
 		if (ret)
 			return ret;
 
-		state->period = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * (1 << resolution) *
+		state->period = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * ((1 << resolution) - 1) *
 						 pre_div * (1 << m), refclk);
 		state->duty_cycle = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * pwm_value * pre_div * (1 << m), refclk);
 	} else {