ath10k and min_gcd + adhoc issues in 4.20 kernel

[Ben Greear <greearb@candelatech.com>]

I just updated to 4.20 and ported forward my ath10k patches.  Now the driver
will not register with mac80211 because this warning hits in net/wireless/core.c:

			/*
			 * This isn't well-defined right now. If you have an
			 * IBSS interface, then its beacon interval may change
			 * by joining other networks, and nothing prevents it
			 * from doing that.
			 * So technically we probably shouldn't even allow AP
			 * and IBSS in the same interface, but it seems that
			 * some drivers support that, possibly only with fixed
			 * beacon intervals for IBSS.
			 */
			if (WARN_ON(types & BIT(NL80211_IFTYPE_ADHOC) &&
				    c->beacon_int_min_gcd)) {
				return -EINVAL;
			}


It looks like this was triggered by:

Commit 0c317a02ca982ca093e71bf07cb562265ba40032
Author: Purushottam Kushwaha <pkushwah@qti.qualcomm.com>
Date:   Wed Oct 12 18:26:51 2016 +0530

     cfg80211: support virtual interfaces with different beacon intervals

and

commit 8ebee73b574ad3dd1f14d461f65ceaffbd637650
Author: Anilkumar Kolli <akolli@codeaurora.org>
Date:   Wed Mar 28 12:19:40 2018 +0300

     ath10k: advertize beacon_int_min_gcd


To be honest, I don't see why that check for beacon_int_min_gcd is in the registration
logic.  Having it be '1' means that the driver/nic/firmware is flexible on pretty much
any combination of beacon interval, so why should that trigger the WARN_ON case?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com