gpu: ion: Add support for flushing via fd

Userspace clients pass fds around, not handles. Support flushing
via fd.

Change-Id: Ic22d9327e9fa72cb604c3010a2a6f798be8dfdb1
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>

include/linux/ion.h

@@ -411,6 +411,7 @@ struct ion_custom_data {
 /* struct ion_flush_data - data passed to ion for flushing caches
  *
  * @handle:	handle with data to flush
+ * @fd:		fd to flush
  * @vaddr:	userspace virtual address mapped with mmap
  * @offset:	offset into the handle to flush
  * @length:	length of handle to flush
@@ -421,6 +422,7 @@ struct ion_custom_data {
  */
 struct ion_flush_data {
 	struct ion_handle *handle;
+	int fd;
 	void *vaddr;
 	unsigned int offset;
 	unsigned int length;