omap: iovmm: Add missing mutex_unlock

I was using Coccinelle with the mutex_unlock semantic patch, and it
unconvered this problem. It appears to be a valid missing unlock issue.
This change should correct it by moving the unlock below the label.

This patch is against the mainline kernel.

Cc: Julia Lawall <julia@diku.dk>
Cc: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: NDaniel Walker <dwalker@fifo99.com>
Signed-off-by: NKevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>

arch/arm/plat-omap/iovmm.c

@@ -363,8 +363,9 @@ void *da_to_va(struct iommu *obj, u32 da)
 		goto out;
 	}
 	va = area->va;
-	mutex_unlock(&obj->mmap_lock);
 out:
+	mutex_unlock(&obj->mmap_lock);
+
 	return va;
 }
 EXPORT_SYMBOL_GPL(da_to_va);