bpf: Handle allocation failure in acquire_lock_state

The acquire_lock_state function needs to handle possible NULL values
returned by acquire_reference_state, and return -ENOMEM.

Fixes: 769b0f1c ("bpf: Refactor {acquire,release}_reference_state")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250206105435.2159977-24-memxor@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>