binder: relocate low space calculation

Move the low async space calculation to debug_low_async_space_locked().
This logic not only fits better here but also offloads some of the many
tasks currently done in binder_alloc_new_buf_locked().

No functional change in this patch.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-15-cmllamas@google.com


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