w1: mxc_w1: Fix mxc_w1_ds2_reset_bus() return value

This patch fix mxc_w1_ds2_reset_bus() return value.
According to i.MX reference manual, "presence status" reflected
in the bit 6 of control register.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/w1/masters/mxc_w1.c

@@ -74,7 +74,7 @@ static u8 mxc_w1_ds2_reset_bus(void *data)
 
 		udelay(100);
 	}
-	return (reg_val >> 7) & 0x1;
+	return (reg_val >> 6) & 0x1;
 }
 
 /*