s4:torture: Initialize struct wrepl_wins_name

s4:torture: Initialize struct wrepl_wins_name

"Error: UNINIT (CWE-457):
samba-4.20.0rc2/source4/torture/nbt/winsreplication.c:6759: var_decl: Declaring variable ""wins_name_"" without initializer.
samba-4.20.0rc2/source4/torture/nbt/winsreplication.c:6760: assign: Assigning: ""wins_name"" = ""&wins_name_"", which points to uninitialized data.
samba-4.20.0rc2/source4/torture/nbt/winsreplication.c:9455: uninit_use_in_call: Using uninitialized value ""*wins_name"". Field ""wins_name->is_group"" is uninitialized when calling ""test_wrepl_update_one"".
 9453|   		wins_name->unknown	= ""255.255.255.255"";
 9454|
 9455|-> 		ret &= test_wrepl_update_one(tctx, ctx, &ctx->b, wins_name);
 9456|
 9457|   		/*"

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Noel Power <npower@samba.org>