libcamera: control_serializer: Fix usage of uninitialized variable

The idMap variable may be used uninitialized in the
ControlSerializer::deserialize<ControlList>() function as reported by
gcc 11:

../../src/libcamera/control_serializer.cpp: In member function ‘T libcamera::ControlSerializer::deserialize(libcamera::ByteStreamBuffer&) [with T = libcamera::ControlList]’:
../../src/libcamera/control_serializer.cpp:609:33: error: ‘idMap’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  609 |         ControlList ctrls(*idMap);
      |

This is due to a missing default case in a switch/case. Fix it by adding
the default case.

Fixes: 6b1404fc4836 ("libcamera: control_serializer: Fix usage of uninitialized variable")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/control_serializer.cpp

@@ -594,6 +594,7 @@ ControlList ControlSerializer::deserialize<ControlList>(ByteStreamBuffer &buffer
 			break;
 
 		case IPA_CONTROL_ID_MAP_V4L2:
+		default:
 			LOG(Serializer, Fatal)
 				<< "A list of V4L2 controls requires an ControlInfoMap";
 			return {};