pwm: ftm: Correctly track usage count

No matter how many times the FTM PWM is enabled, the use_count will
always be one.
Signed-off-by: NXiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-fsl-ftm.c

@@ -299,7 +299,7 @@ static int fsl_counter_clock_enable(struct fsl_pwm_chip *fpc)
 {
 	int ret;
 
-	if (fpc->use_count != 0)
+	if (fpc->use_count++ != 0)
 		return 0;
 
 	/* select counter clock source */
@@ -316,8 +316,6 @@ static int fsl_counter_clock_enable(struct fsl_pwm_chip *fpc)
 		return ret;
 	}
 
-	fpc->use_count++;
-
 	return 0;
 }