P2P: Allow PSK to be used instead of passphrase for persistent GO

P2P: Allow PSK to be used instead of passphrase for persistent GO

This continues optimizations for use of CPU heavy pbkdf2_sha1() in GO
setup after the earlier commit 30c371e8a54c3b1bece6366ff0666da15d63e45e
by allowing PSK to be used instead of passphrase when creating
persistent group information manually for the GO.

It should be noted that this would not meet the requirements in the P2P
specification (GO shall maintain the passphrase), so this should be used
only when there is no need to allow manual configuration of legacy STAs
using the passphrase.

Signed-hostap: Masashi Honma <masashi.honma@gmail.com>