[zircon] Remove explicit initializers for flexible array members

These are not allowed by a strict compiler.

Change-Id: I28790cd46a852f5eeb8a3d55a24b2b44d0cd80f3
diff --git a/zircon/system/dev/nand/nandpart/test/nandpart-utils-test.cpp b/zircon/system/dev/nand/nandpart/test/nandpart-utils-test.cpp
index 46f914e..b1e3d2e 100644
--- a/zircon/system/dev/nand/nandpart/test/nandpart-utils-test.cpp
+++ b/zircon/system/dev/nand/nandpart/test/nandpart-utils-test.cpp
@@ -32,7 +32,6 @@
         .partition_count = partition_count,
         .reserved = 0,
         .guid = {},
-        .partitions = {},
     };
 }
 
diff --git a/zircon/system/ulib/hid-parser/parser.cpp b/zircon/system/ulib/hid-parser/parser.cpp
index f02240e..e9146e4 100644
--- a/zircon/system/ulib/hid-parser/parser.cpp
+++ b/zircon/system/ulib/hid-parser/parser.cpp
@@ -165,7 +165,7 @@
         if (mem == nullptr)
             return kParseNoMemory;
 
-        auto dev = new (mem) DeviceDescriptor{report_count, {}};
+        auto dev = new (mem) DeviceDescriptor{report_count};
 
         mem += device_sz;
         auto dest_fields = reinterpret_cast<ReportField*>(mem);