BACKPORT: Revert "binder: switch alloc->mutex to spinlock_t"

This reverts commit 7710e2cc.

In preparation for concurrent page installations, restore the original
alloc->mutex which will serialize zap_page_range_single() against page
installations in subsequent patches (instead of the mmap_sem).

Resolved trivial conflicts with commit 2c10a20f ("binder_alloc: Fix
sleeping function called from invalid context") and commit da0c0251
("mm/list_lru: simplify the list_lru walk callback function").

Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-2-cmllamas@google.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 410746221
Bug: 451778078
(cherry picked from commit 8b52c726)
[cmllamas: fixed trivial merge conflicts]
Change-Id: I19c66787214a2863b687a3ec0ee787affeb77eb5
Signed-off-by: Carlos Llamas <cmllamas@google.com>