mfd: rz-mtu3: Reduce critical sections

Reduce critical sections on rz_mtu3_start_stop_ch() and
rz_mtu3_is_enabled() by moving offset and bitpos computation
outside the critical section and drop the 'ret' variable on
rz_mtu3_is_enabled() and return 'tstr & BIT(bitpos)' directly.

Reported-by: Pavel Machek <[e-mail]>
Closes: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Biju Das <[e-mail]>
Reviewed-by: Pavel Machek <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/rz-mtu3.c

···
 	u16 offset;
 	u8 bitpos;
 
+	offset = rz_mtu3_get_tstr_offset(ch);
+	bitpos = rz_mtu3_get_tstr_bit_pos(ch);
+
 	/* start stop register shared by multiple timer channels */
 	raw_spin_lock_irqsave(&priv->lock, flags);
 
-	offset = rz_mtu3_get_tstr_offset(ch);
-	bitpos = rz_mtu3_get_tstr_bit_pos(ch);
 	tstr = rz_mtu3_shared_reg_read(ch, offset);
 	__assign_bit(bitpos, &tstr, start);
 	rz_mtu3_shared_reg_write(ch, offset, tstr);
···
 	struct rz_mtu3 *mtu = dev_get_drvdata(ch->dev->parent);
 	struct rz_mtu3_priv *priv = mtu->priv_data;
 	unsigned long flags, tstr;
-	bool ret = false;
 	u16 offset;
 	u8 bitpos;
 
-	/* start stop register shared by multiple timer channels */
-	raw_spin_lock_irqsave(&priv->lock, flags);
-
 	offset = rz_mtu3_get_tstr_offset(ch);
 	bitpos = rz_mtu3_get_tstr_bit_pos(ch);
-	tstr = rz_mtu3_shared_reg_read(ch, offset);
-	ret = tstr & BIT(bitpos);
 
+	/* start stop register shared by multiple timer channels */
+	raw_spin_lock_irqsave(&priv->lock, flags);
+	tstr = rz_mtu3_shared_reg_read(ch, offset);
 	raw_spin_unlock_irqrestore(&priv->lock, flags);
 
-	return ret;
+	return tstr & BIT(bitpos);
 }
 EXPORT_SYMBOL_GPL(rz_mtu3_is_enabled);