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]

Signed-off-by: Vishal Mahaveer <vishalm@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>

[Ported to JB MR2 and squashed with following changes]

[Vishal Mahaveer <vishalm@ti.com>]
    wifi: avoid crash when no phy's are found

[modified for KK and squashed with following changes]

[Barak Bercovitz <barak@wizery.com>]
    wifi: remove p2p interface on supplicant stop

Change-Id: I2ccbae3cf00fb6e96a3de4443a3dafcc5376f9b3
Signed-off-by: Eyal Reizer <eyalr@ti.com>