backports: add missing header file

The act8865 regulator driver needs this header file.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
diff --git a/copy-list b/copy-list
index 9ec4f4b..307ab00 100644
--- a/copy-list
+++ b/copy-list
@@ -133,6 +133,7 @@
 # regulator routines are defined via the header file
 # include/linux/regulator/consumer.h and dummy.h
 include/linux/regulator/ab8500.h
+include/linux/regulator/act8865.h
 include/linux/regulator/db8500-prcmu.h
 include/linux/regulator/fan53555.h
 include/linux/regulator/gpio-regulator.h