wifi: support adding p2p0 when starting wpa_supplicant

Add p2p0 using an NL80211 command when wpa_supplicant is started, and
p2p_supported is enabled.

[vishalm@ti.com: Added the changes inside ifdef]

[Ported to JB MR2 and squashed with following changes]

[Vishal Mahaveer <vishalm@ti.com>]
    wifi: avoid crash when no phy's are found
wifi: remove p2p interface on supplicant stop

remove p2p interface on wpa_supplicant stop
so next time it is started it won't fail when trying
to create p2p again