Bluetooth: Remove bogus check for pending mgmt Set HS command

The command handler for Set HS doesn't use mgmt_pending_add() so we can
never have a pending Set HS command that mgmt_pending_find() would
return. This patch removes an unnecessary lookup for it in the set_ssp()
handler function.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>