Revert "arm64/uprobes: change the uprobe_opcode_t typedef to fix the sparse warning"

This reverts commit 354b3847 which is
commit ef08c0fa upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Icaca1349a9483085afa6a282dd303efb138f64ba
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>