fix reference IsConvolution2dSupported error messages
fix reference IsConvolution2dSupported error messages

Signed-off-by: Les Bell <4220b27cfa121126d2566f38c0dc19019d3709a8@arm.com>
Change-Id: Id454ac91ae1c0216f5ecfa1c3cde9430691f51f4

ARM-software/armnn,ARM-software/armnn,ARM-software/armnn