Split MOUNT_FLAG_VISIBLE into MOUNT_FLAG_VISIBLE_FOR_{READ, WRITE}

IVold.MOUNT_FLAG_VISIBLE is split into MOUNT_FLAG_VISIBLE_FOR_READ and
MOUNT_FLAG_VISIBLE_FOR_WRITE.
Accordingly, VolumeBase::MountFlags::kVisible is split into
kVisibleForRead and kVisibleForWrite.

Bug: 206019156
Test: m
Change-Id: Ia55673400d9f713f221650e1335a46ba11f6f027
Merged-In: Ia55673400d9f713f221650e1335a46ba11f6f027
diff --git a/binder/android/os/IVold.aidl b/binder/android/os/IVold.aidl
index 606f473..8dd7860 100644
--- a/binder/android/os/IVold.aidl
+++ b/binder/android/os/IVold.aidl
@@ -159,7 +159,8 @@
     const int FSTRIM_FLAG_DEEP_TRIM = 1;
 
     const int MOUNT_FLAG_PRIMARY = 1;
-    const int MOUNT_FLAG_VISIBLE = 2;
+    const int MOUNT_FLAG_VISIBLE_FOR_READ = 2;
+    const int MOUNT_FLAG_VISIBLE_FOR_WRITE = 4;
 
     const int PARTITION_TYPE_PUBLIC = 0;
     const int PARTITION_TYPE_PRIVATE = 1;