libcamera: camera: Remove the prepared state

With the FrameBuffer rework completed there is no reason to keep the
camera prepared state around as buffer allocations are now decoupled
from the camera state. Remove the camera state simplifying the API.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

test/camera/buffer_import.cpp

@@ -174,11 +174,6 @@ protected:
 			return TestFail;
 		}
 
-		if (camera_->allocateBuffers()) {
-			std::cout << "Failed to allocate buffers" << std::endl;
-			return TestFail;
-		}
-
 		Stream *stream = cfg.stream();
 
 		BufferSource source;
@@ -244,11 +239,6 @@ protected:
 			return TestFail;
 		}
 
-		if (camera_->freeBuffers()) {
-			std::cout << "Failed to free buffers" << std::endl;
-			return TestFail;
-		}
-
 		return TestPass;
 	}