wil6210: rename p2p_wdev_mutex to vif_mutex

As more support is added for multiple VIFs, there is a need
to protect the wil6210_vif structure from access while it is
deleted (mainly from del_virtual_intf operation).
Instead of adding another mutex, use p2p_wdev_mutex and rename
it to vif_mutex to reflect the added role. Its existing roles
are similar so it extends nicely (for example it protects the
scan_request member which is also a member of wil6210_vif).

Change-Id: Idf7e574817bb53c2033006e28314160e978dd7b1
Signed-off-by: Lior David <liord@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: 404bbb3cca3c269ef392017053a8d4cb83e0cc77
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


[ailizaro@codeaurora.org: trivial conflict fixes]
Signed-off-by: Alexei Avshalom Lazar <ailizaro@codeaurora.org>