wifi: libertas: fix some memleaks in lbs_allocate_cmd_buffer()

In the for statement of lbs_allocate_cmd_buffer(), if the allocation of
cmdarray[i].cmdbuf fails, both cmdarray and cmdarray[i].cmdbuf needs to
be freed. Otherwise, there will be memleaks in lbs_allocate_cmd_buffer().

Fixes: 876c9d3a ("[PATCH] Marvell Libertas 8388 802.11b/g USB driver")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240126075336.2825608-1-alexious@zju.edu.cn