ANDROID: Restore a line removed accidentally during a revert

When reverting commit 9ad8ff90 in
android-mainline (commit 31c9ccb1),
a call to __mutex_remove_waiter() was accidentally removed. That results
in a mutex waiter being left in the wait_list of the mutex in the error
handling path of __mutex_lock_common(). The issue was reproduced by
running controllers.memcg ltp tests and results in a kernel crash that
looks like this:

[  306.207016] list_del corruption. next->prev should be ffffa5f983a479d0, but was ffffa5f983a6f9e8
[  306.207271] ------------[ cut here ]------------
[  306.207328] kernel BUG at lib/list_debug.c:56!

Fix this by restoring the removed line.

Fixes: 31c9ccb1 ("Revert "ANDROID: vendor_hooks: add waiting information for blocked tasks"")
Bug: 199506772
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I49ac82b20405fda0ea7d10fae68402279ad751fa