{nl,cfg}80211: support high bitrates

Until now, a u16 value was used to represent bitrate value.
With VHT bitrates this becomes too small.

Introduce a new 32-bit bitrate attribute. nl80211 will report
both the new and the old attribute, unless the bitrate doesn't
fit into the old u16 attribute in which case only the new one
will be reported.

User space tools encouraged to prefer the 32-bit attribute, if
available (since it won't be available on older kernels.)

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
[reword commit message and comments a bit]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 77102e6..2a5cdb6 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2618,7 +2618,8 @@
 				 int attr)
 {
 	struct nlattr *rate;
-	u16 bitrate;
+	u32 bitrate;
+	u16 bitrate_compat;
 
 	rate = nla_nest_start(msg, attr);
 	if (!rate)
@@ -2626,8 +2627,12 @@
 
 	/* cfg80211_calculate_bitrate will return 0 for mcs >= 32 */
 	bitrate = cfg80211_calculate_bitrate(info);
+	/* report 16-bit bitrate only if we can */
+	bitrate_compat = bitrate < (1UL << 16) ? bitrate : 0;
 	if ((bitrate > 0 &&
-	     nla_put_u16(msg, NL80211_RATE_INFO_BITRATE, bitrate)) ||
+	     nla_put_u32(msg, NL80211_RATE_INFO_BITRATE32, bitrate)) ||
+	    (bitrate_compat > 0 &&
+	     nla_put_u16(msg, NL80211_RATE_INFO_BITRATE, bitrate_compat)) ||
 	    ((info->flags & RATE_INFO_FLAGS_MCS) &&
 	     nla_put_u8(msg, NL80211_RATE_INFO_MCS, info->mcs)) ||
 	    ((info->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH) &&