dma-buf: update debugfs output

Russell King observed 'wierd' looking output from debugfs, and also suggested
better ways of getting device names (use KBUILD_MODNAME, dev_name())

This patch addresses these issues to make the debugfs output correct and better
looking.

While at it, replace seq_printf with seq_puts to remove the checkpatch.pl
warnings.

Reported-by: Russell King - ARM Linux <linux@arm.linux.org.uk>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index dfac5ed..f886985 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -171,7 +171,7 @@
 			       size_t size, int flags, const char *);
 
 #define dma_buf_export(priv, ops, size, flags)	\
-	dma_buf_export_named(priv, ops, size, flags, __FILE__)
+	dma_buf_export_named(priv, ops, size, flags, KBUILD_MODNAME)
 
 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 struct dma_buf *dma_buf_get(int fd);