drivers/base/test: fix global-out-of-bounds error

Commit c032ace7 ("software node: add basic tests for property
entries") introduced a global-out-of-bounds error because it forgot to
add a terminator of "nodes "for software_node_register_nodes() to
process.

 	# Subtest: property-entry
 	1..7
 	ok 1 - pe_test_uints
 	ok 2 - pe_test_uint_arrays
 	ok 3 - pe_test_strings
 	ok 4 - pe_test_bool
 	ok 5 - pe_test_move_inline_u8
 	ok 6 - pe_test_move_inline_str
 ==================================================================
 BUG: KASAN: global-out-of-bounds in
 software_node_register_nodes+0x41/0x80
 Read of size 8 at addr ffffffff989ef250 by task kunit_try_catch/316

 CPU: 17 PID: 316 Comm: kunit_try_catch Not tainted
 5.5.0-rc4-next-20200106+ #1
 Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40
 03/09/2018
 Call Trace:
  dump_stack+0xa0/0xea
  print_address_description.constprop.5.cold.7+0x64/0x384
  __kasan_report.cold.8+0x7a/0xc0
  kasan_report+0x12/0x20
  __asan_load8+0x71/0xa0
  software_node_register_nodes+0x41/0x80
  pe_test_reference+0x1eb/0x1200
  kunit_try_run_case+0x6b/0xd1
  kunit_generic_run_threadfn_adapter+0x29/0x50
  kthread+0x1e6/0x210
  ret_from_fork+0x27/0x50

 The buggy address belongs to the variable:
  nodes.21544+0x30/0x920

 Memory state around the buggy address:
  ffffffff989ef100: fa fa fa fa 00 04 fa fa fa fa fa fa 00 00 00 00
  ffffffff989ef180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 >ffffffff989ef200: fa fa fa fa 00 00 00 00 00 00 fa fa fa fa fa fa
                                                  ^
  ffffffff989ef280: 00 06 fa fa fa fa fa fa 00 00 04 fa fa fa fa fa
  ffffffff989ef300: 00 00 fa fa fa fa fa fa 00 05 fa fa fa fa fa fa
 ==================================================================
 Disabling lock debugging due to kernel taint
 	ok 7 - pe_test_reference
 ok 8 - property-entry

Fixes: c032ace7 ("software node: add basic tests for property entries")
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>