brcmfmac: Delete useless kfree code

A null pointer will be passed to a kfree() call after a kzalloc() call failed.
This code is useless. Thus delete the extra function call.

A goto statement is also no longer needed. Thus adjust an if branch.

Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201222135113.20680-1-zhengyongjun3@huawei.com