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

This reverts commit 9085d7ea which is
commit ef08c0fadd8a17ebe429b85e23952dac3263ad34 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: I4113669a7569a6cddddf224de40e3693479e541f
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>