ANDROID: GKI: add set_page_private to virtual_device abi list

In the back-merge from android15-6.6, the virtio_balloon.ko module now
needs access to the set_page_private symbol.  As this is already part of
the abi list for a different target, also add it to the
abi_gki_aarch64_virtual_device file to fix the build.

Fixes: ae3d391a ("Merge branch 'android15-6.6' into android15-6.6-lts")
Change-Id: I6e04b1e712599fd2a18f480a580f4249a2be4148
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
(cherry picked from commit a5814321)
Bug: 389225080