mei: revamp mei_data2slots

1. Move the mei_data2slots to mei_dev.h as it will be used
by the all supported HW.
2. Change return value from u8 to u32 to catch possible overflows
3. Eliminate computing the slots number twice in the same function

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index cb80166..09a2af4 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -374,6 +374,17 @@
 	return msecs_to_jiffies(sec * MSEC_PER_SEC);
 }
 
+/**
+ * mei_data2slots - get slots - number of (dwords) from a message length
+ *	+ size of the mei header
+ * @length - size of the messages in bytes
+ * returns  - number of slots
+ */
+static inline u32 mei_data2slots(size_t length)
+{
+	return DIV_ROUND_UP(sizeof(struct mei_msg_hdr) + length, 4);
+}
+
 
 /*
  * mei init function prototypes