media: iris: Fix use-after-free in iris_release_internal_buffers()

In the Linux kernel, the following vulnerability has been resolved:

media: iris: Fix use-after-free in iris_release_internal_buffers()

The recent change in commit 1dabf00ee206 ("media: iris: gen1: Destroy

internal buffers after FW releases") introduced a regression where

session_release_buf() may free the buffer. The caller,

iris_release_internal_buffers(), continued to access `buffer` after the

call, leading to a potential use-after-free.

Fix this by setting BUF_ATTR_PENDING_RELEASE before calling

session_release_buf(), and reverting the flag if the call fails. This

ensures no dereference occurs after potential freeing.