flash: Rename free_flash_dev to flash_dev_free

Change-Id: I3d3da6312217b6b869fa3f62a1d4752be98fd609
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/flash.c b/flash.c
index 63a1293..c446658 100644
--- a/flash.c
+++ b/flash.c
@@ -97,7 +97,7 @@
 	return rc;
 }
 
-void free_flash_dev(struct mbox_context *context)
+void flash_dev_free(struct mbox_context *context)
 {
 	free(context->flash_bmap);
 	close(context->fds[MTD_FD].fd);