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>

test/compression.c

@@ -457,7 +457,7 @@ static int compress_using_none(struct unit_test_state *uts,
  *
  * @comp_type:	Compression type to test
  * @compress:	Our function to compress data
- * @return 0 if OK, non-zero on failure
+ * Return: 0 if OK, non-zero on failure
  */
 static int run_bootm_test(struct unit_test_state *uts, int comp_type,
 			  mutate_func compress)