mt76: mt7915: fix txrate reporting

mainline inclusion
from mainline-v5.13-rc1
commit f43b941f
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I94J23
CVE: CVE-2021-47028

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f43b941fd61003659a3f0e039595e5e525917aa8



--------------------------------

Properly check rate_info to fix unexpected reporting.

[ 1215.161863] Call trace:
[ 1215.164307]  cfg80211_calculate_bitrate+0x124/0x200 [cfg80211]
[ 1215.170139]  ieee80211s_update_metric+0x80/0xc0 [mac80211]
[ 1215.175624]  ieee80211_tx_status_ext+0x508/0x838 [mac80211]
[ 1215.181190]  mt7915_mcu_get_rx_rate+0x28c/0x8d0 [mt7915e]
[ 1215.186580]  mt7915_mac_tx_free+0x324/0x7c0 [mt7915e]
[ 1215.191623]  mt7915_queue_rx_skb+0xa8/0xd0 [mt7915e]
[ 1215.196582]  mt76_dma_cleanup+0x7b0/0x11d0 [mt76]
[ 1215.201276]  __napi_poll+0x38/0xf8
[ 1215.204668]  napi_workfn+0x40/0x80
[ 1215.208062]  process_one_work+0x1fc/0x390
[ 1215.212062]  worker_thread+0x48/0x4d0
[ 1215.215715]  kthread+0x120/0x128
[ 1215.218935]  ret_from_fork+0x10/0x1c

Fixes: e57b7901 ("mt76: add mac80211 driver for MT7915 PCIe-based chipsets")
Fixes: e4c5ead6 ("mt76: mt7915: rename mt7915_mcu_get_rate_info to mt7915_mcu_get_tx_rate")
Reported-by: Evelyn Tsai <evelyn.tsai@mediatek.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>