move arm64 gki-ramdisk.cpio to arm64/

To prepare for gki-ramdisks supporting other architectures, move
the arm64 gki-ramdisk to the arm64 directory.
diff --git a/gki-ramdisk.cpio b/arm64/gki-ramdisk.cpio
similarity index 100%
rename from gki-ramdisk.cpio
rename to arm64/gki-ramdisk.cpio
Binary files differ