Bluetooth: MGMT: Fix always using HCI_MAX_AD_LENGTH

[ Upstream commit 112b5090 ]

HCI_MAX_AD_LENGTH shall only be used if the controller doesn't support
extended advertising, otherwise HCI_MAX_EXT_AD_LENGTH shall be used
instead.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Stable-dep-of: 2ab3e8d6 ("Bluetooth: Fix eir name length")
Signed-off-by: Sasha Levin <sashal@kernel.org>