Bluetooth: hci_conn: Remove alloc from critical section

This removes the kzalloc memory allocation inside critical section in
create_pa_sync, fixing the following message that appears when the kernel
is compiled with CONFIG_DEBUG_ATOMIC_SLEEP enabled:

BUG: sleeping function called from invalid context at
include/linux/sched/mm.h:321

Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>