fix: kprobes: Remove kretprobe hash (v5.11)

fix: kprobes: Remove kretprobe hash (v5.11)

See upstream commit:

  commit d741bf41d7c7db4898bacfcb020353cddc032fd8
  Author: Peter Zijlstra <peterz@infradead.org>
  Date:   Sat Aug 29 22:03:24 2020 +0900

    kprobes: Remove kretprobe hash

    The kretprobe hash is mostly superfluous, replace it with a per-task
    variable.

    This gets rid of the task hash and it's related locking.

    Note that this may change the kprobes module-exported API for kretprobe
    handlers. If any out-of-tree kretprobe user uses ri->rp, use
    get_kretprobe(ri) instead.

Link: https://lore.kernel.org/r/159870620431.1229682.16325792502413731312.stgit@devnote2
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I855765f390ad7caf481ef5fea334645e852f5b0f