camera3: Update maxRegions tag.

Change-Id: I22501cbf7f941d9626b88182e2dda8a13a620d01
diff --git a/libcamera2/ExynosCamera2.cpp b/libcamera2/ExynosCamera2.cpp
index 7aadf98..da68fa4 100644
--- a/libcamera2/ExynosCamera2.cpp
+++ b/libcamera2/ExynosCamera2.cpp
@@ -588,9 +588,9 @@
     ADD_OR_SIZE(ANDROID_CONTROL_AVAILABLE_EFFECTS,
             availableEffects, sizeof(availableEffects));
 
-    int32_t max3aRegions = 1;
+    static const int32_t max3aRegions[] = {/*AE*/ 1,/*AWB*/ 1,/*AF*/ 1};
     ADD_OR_SIZE(ANDROID_CONTROL_MAX_REGIONS,
-            &max3aRegions, 1);
+            max3aRegions, sizeof(max3aRegions)/sizeof(max3aRegions[0]));
 
     ADD_OR_SIZE(ANDROID_CONTROL_AE_AVAILABLE_MODES,
             m_curCameraInfo->availableAeModes, m_curCameraInfo->numAvailableAeModes);