mfd: Remove unneeded io_mutex from struct twl6040

Current code has been converted to use regmap APIs, the io_mutex is not needed.
Thus remove the io_mutex.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/twl6040-core.c b/drivers/mfd/twl6040-core.c
index 4ded9e7..5f620ae 100644
--- a/drivers/mfd/twl6040-core.c
+++ b/drivers/mfd/twl6040-core.c
@@ -64,19 +64,15 @@
 	int ret;
 	unsigned int val;
 
-	mutex_lock(&twl6040->io_mutex);
 	/* Vibra control registers from cache */
 	if (unlikely(reg == TWL6040_REG_VIBCTLL ||
 		     reg == TWL6040_REG_VIBCTLR)) {
 		val = twl6040->vibra_ctrl_cache[VIBRACTRL_MEMBER(reg)];
 	} else {
 		ret = regmap_read(twl6040->regmap, reg, &val);
-		if (ret < 0) {
-			mutex_unlock(&twl6040->io_mutex);
+		if (ret < 0)
 			return ret;
-		}
 	}
-	mutex_unlock(&twl6040->io_mutex);
 
 	return val;
 }
@@ -86,12 +82,10 @@
 {
 	int ret;
 
-	mutex_lock(&twl6040->io_mutex);
 	ret = regmap_write(twl6040->regmap, reg, val);
 	/* Cache the vibra control registers */
 	if (reg == TWL6040_REG_VIBCTLL || reg == TWL6040_REG_VIBCTLR)
 		twl6040->vibra_ctrl_cache[VIBRACTRL_MEMBER(reg)] = val;
-	mutex_unlock(&twl6040->io_mutex);
 
 	return ret;
 }
@@ -99,23 +93,13 @@
 
 int twl6040_set_bits(struct twl6040 *twl6040, unsigned int reg, u8 mask)
 {
-	int ret;
-
-	mutex_lock(&twl6040->io_mutex);
-	ret = regmap_update_bits(twl6040->regmap, reg, mask, mask);
-	mutex_unlock(&twl6040->io_mutex);
-	return ret;
+	return regmap_update_bits(twl6040->regmap, reg, mask, mask);
 }
 EXPORT_SYMBOL(twl6040_set_bits);
 
 int twl6040_clear_bits(struct twl6040 *twl6040, unsigned int reg, u8 mask)
 {
-	int ret;
-
-	mutex_lock(&twl6040->io_mutex);
-	ret = regmap_update_bits(twl6040->regmap, reg, mask, 0);
-	mutex_unlock(&twl6040->io_mutex);
-	return ret;
+	return regmap_update_bits(twl6040->regmap, reg, mask, 0);
 }
 EXPORT_SYMBOL(twl6040_clear_bits);
 
@@ -573,7 +557,6 @@
 	twl6040->irq = client->irq;
 
 	mutex_init(&twl6040->mutex);
-	mutex_init(&twl6040->io_mutex);
 	init_completion(&twl6040->ready);
 
 	twl6040->rev = twl6040_reg_read(twl6040, TWL6040_REG_ASICREV);