mwifiex: fix simultaneous assoc and scan issue

When scan and assoc (infra/ibss) commands are simultaneously
given in two terminals, association response is erroneously
served while serving the scan response.

mwifiex_cfg80211_results() is the common routine for sending
ioctl (scan, assoc etc.) results to cfg80211 stack. In above
scenario even if the common routine is called for scan ioctl
context, it also tries to send information about assoc ioctl to
cfg80211 because "priv->assoc_request/priv->ibss_join_request"
flag is on at that time.

Fix the issue by updating request variable after assoc handling
and modifying the variable check in mwifiex_cfg80211_results.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kiran Divekar <dkiran@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>