Revert "O is API 26"

This reverts commit 8713882bb8d082f997fa68b75606caa48a45862d.

Reason for revert:  b/37355569

Bug: 37480230
Bug: 37896931
Bug: 37355569
Change-Id: Ic07d948fd0b4a0a8434e1f4f0c8e559c4258cf5e
diff --git a/Android.mk b/Android.mk
index b7db00b..dd37341 100644
--- a/Android.mk
+++ b/Android.mk
@@ -10,7 +10,7 @@
 # is made which breaks compatibility with the previous platform sepolicy version,
 # not just on every increase in PLATFORM_SDK_VERSION.  The minor version should
 # be reset to 0 on every bump of the PLATFORM_SDK_VERSION.
-sepolicy_major_vers := 26
+sepolicy_major_vers := 25
 sepolicy_minor_vers := 0
 
 ifneq ($(sepolicy_major_vers), $(PLATFORM_SDK_VERSION))