nfp: bpf: Add check for nfp_app_ctrl_msg_alloc()

Add check for the return value of nfp_app_ctrl_msg_alloc() in
nfp_bpf_cmsg_alloc() to prevent null pointer dereference.

Fixes: ff3d43f7 ("nfp: bpf: implement helpers for FW map ops")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Link: https://patch.msgid.link/20250218030409.2425798-1-haoxiang_li2024@163.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>