doc: replace @return by Return:

Sphinx expects Return: and not @return to indicate a return value.

find . -name '*.c' -exec \
sed -i 's/^\(\s\)\*\(\s*\)@return\(\s\)/\1*\2Return:\3/' {} \;

find . -name '*.h' -exec \
sed -i 's/^\(\s\)\*\(\s*\)@return\(\s\)/\1*\2Return:\3/' {} \;

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/common/board_r.c b/common/board_r.c
index 60eced6..c24d9b4 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -418,7 +418,7 @@
  * NOTE: Loading the environment early can be a bad idea if security is
  *       important, since no verification is done on the environment.
  *
- * @return 0 if environment should not be loaded, !=0 if it is ok to load
+ * Return: 0 if environment should not be loaded, !=0 if it is ok to load
  */
 static int should_load_env(void)
 {