Build only when using LegacyCamera

LegacyCamera can't be built into the new Gallery2 app
We will use the MR0 Gallery2 instead named LegacyGallery2

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: Ia1e4b1eb54ae406ecb2b4f5ce8d268f18b1c3d89