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

This reverts commit 0e13fe42 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: Ic765621defd3a5b1d26313b4e95a1d6acdea1450
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>