i2c: designware-baytrail: fix potential null pointer dereference on dev

The assignment to addr requires a call to get_sem_addr that dereferences
dev, however, this dereference occurs before a null pointer check on dev.
Move this assignment after the null check on dev to avoid a potential null
pointer dereference.

Detected by CoverityScan, CID#1419700 ("Dereference before null check")

Fixes: fd476fa22a1f432 ("i2c: designware-baytrail: Add support for cherrytrail")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-designware-baytrail.c

@@ -70,7 +70,7 @@ static void reset_semaphore(struct dw_i2c_dev *dev)
 
 static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
 {
-	u32 addr = get_sem_addr(dev);
+	u32 addr;
 	u32 sem = PUNIT_SEMAPHORE_ACQUIRE;
 	int ret;
 	unsigned long start, end;
@@ -94,6 +94,8 @@ static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
 	 */
 	pm_qos_update_request(&dev->pm_qos, 0);
 
+	addr = get_sem_addr(dev);
+
 	/* host driver writes to side band semaphore register */
 	ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, addr, sem);
 	if (ret) {