iwlwifi: mvm: add terminate entry for dmi_system_id tables

Make sure dmi_system_id tables are NULL terminated. This crashed when LTO was enabled:

BUG: KASAN: global-out-of-bounds in dmi_check_system+0x5a/0x70
Read of size 1 at addr ffffffffc16af750 by task NetworkManager/1913

CPU: 4 PID: 1913 Comm: NetworkManager Not tainted 5.12.0-rc1+ #10057
Hardware name: LENOVO 20THCTO1WW/20THCTO1WW, BIOS N2VET27W (1.12 ) 12/21/2020
Call Trace:
 dump_stack+0x90/0xbe
 print_address_description.constprop.0+0x1d/0x140
 ? dmi_check_system+0x5a/0x70
 ? dmi_check_system+0x5a/0x70
 kasan_report.cold+0x7b/0xd4
 ? dmi_check_system+0x5a/0x70
 __asan_load1+0x4d/0x50
 dmi_check_system+0x5a/0x70
 iwl_mvm_up+0x1360/0x1690 [iwlmvm]
 ? iwl_mvm_send_recovery_cmd+0x270/0x270 [iwlmvm]
 ? setup_object.isra.0+0x27/0xd0
 ? kasan_poison+0x20/0x50
 ? ___slab_alloc.constprop.0+0x483/0x5b0
 ? mempool_kmalloc+0x17/0x20
 ? ftrace_graph_ret_addr+0x2a/0xb0
 ? kasan_poison+0x3c/0x50
 ? cfg80211_iftype_allowed+0x2e/0x90 [cfg80211]
 ? __kasan_check_write+0x14/0x20
 ? mutex_lock+0x86/0xe0
 ? __mutex_lock_slowpath+0x20/0x20
 __iwl_mvm_mac_start+0x49/0x290 [iwlmvm]
 iwl_mvm_mac_start+0x37/0x50 [iwlmvm]
 drv_start+0x73/0x1b0 [mac80211]
 ieee80211_do_open+0x53e/0xf10 [mac80211]
 ? ieee80211_check_concurrent_iface+0x266/0x2e0 [mac80211]
 ieee80211_open+0xb9/0x100 [mac80211]
 __dev_open+0x1b8/0x280

Fixes: a2ac0f48 ("iwlwifi: mvm: implement approved list for the PPAG feature")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Victor Michel <vic.michel.web@gmail.com>
Acked-by: Luca Coelho <luciano.coelho@intel.com>
[kvalo@codeaurora.org: improve commit log]
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210223140039.1708534-1-weiyongjun1@huawei.com

drivers/net/wireless/intel/iwlwifi/mvm/fw.c

@@ -1083,6 +1083,7 @@ static const struct dmi_system_id dmi_ppag_approved_list[] = {
 			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTek COMPUTER INC."),
 		},
 	},
+	{}
 };
 
 static int iwl_mvm_ppag_init(struct iwl_mvm *mvm)