FROMGIT: binder: fix async space check for 0-sized buffers

Move the padding of 0-sized buffers to an earlier stage to account for
this round up during the alloc->free_async_space check.

Fixes: 74310e06 ("android: binder: Move buffer out of area shared with user space")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-5-cmllamas@google.com


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

Bug: 254650075
(cherry picked from commit 3091c21d
 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git


 char-misc-next)
Change-Id: I0c3a2378fb7e9c534ffe015dee849196f83aa252
Signed-off-by: Carlos Llamas <cmllamas@google.com>