mwifiex: fix missing tsf_val TLV

In mwifiex_cmd_append_tsf_tlv(), two tsf_val TLVs should be
filled in the buffer and then sent to firmware.

The missing first TLV for tsf_val is added back in this patch.

Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>