wifi: mt76: npu: Add missing rx_token_size initialization

wifi: mt76: npu: Add missing rx_token_size initialization

[ Upstream commit 25e3203a2192f2b0d697b2410126bad87e62d4f0 ]

Add missing rx_token_size initialization for NPU offloading.

Fixes: 7fb554b1b623 ("wifi: mt76: Introduce the NPU generic layer")
Tested-by: Kang Yang <kang.yang@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260122-mt76-npu-eagle-offload-v2-2-2374614c0de6@kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>