libcamera: v4l2_videodevice: Rename exportBuffers() to allocateBuffers()

To prepare for the rework of buffer allocation that will differentiate
export and allocation, rename exportBuffers() to allocateBuffers().

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

test/v4l2_videodevice/request_buffers.cpp

@@ -18,7 +18,7 @@ protected:
 	{
 		const unsigned int bufferCount = 8;
 
-		int ret = capture_->exportBuffers(bufferCount, &buffers_);
+		int ret = capture_->allocateBuffers(bufferCount, &buffers_);
 		if (ret != bufferCount)
 			return TestFail;