ANDROID: vfs: fix export symbol type

In commit 04436665 ("ANDROID: vfs: Add setattr2 for filesystems with
per mount permissions") a new symbol was exported, but it should have
been set as a _GPL symbol.

Fix this up by properly.

Bug: 35848445
Cc: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I87585ad059367aa51b784ec415a1bf7f809de769