cfg80211: Correct API cfg80211_vendor_cmd_reply_skb

Correct the definition of API cfg80211_vendor_cmd_reply_skb. Use the
correct value of command and attribute. This fixes the merge error when
open source commit ad7e718c9b4f717823fd920a0103f7b0fb06183f was pulled
into the tree.

Change-Id: Ibe83feba088fa6933bbef7a6c79cd72e6eda64b0
Signed-off-by: Amar Singhal <asinghal@codeaurora.org>