nl80211: Correct the usage of command NL80211_CMD_VENDOR

Add the flag NL80211_FLAG_NEED_WIPHY to the doit definition of
NL80211_CMD_VENDOR. Also assign/pass the cur_cmd_info parameter
correctly. This fixes a merge error when open source commit
ad7e718c was pulled into the tree.

CRs-Fixed: 630797
Change-Id: I2a5a2a93ad3e95ff0d0c56edb9af6af2f71eac4b
Signed-off-by: Amar Singhal <asinghal@codeaurora.org>