ByteBuffer: Remove pointer() in favor of data()

We had two ways to get the data inside a ByteBuffer. That was silly.

Kernel/KSyms.cpp

@@ -34,7 +34,7 @@ static void load_ksyms_from_data(const ByteBuffer& buffer)
 {
     ksym_lowest_address = 0xffffffff;
     ksym_highest_address = 0;
-    auto* bufptr = (const char*)buffer.pointer();
+    auto* bufptr = (const char*)buffer.data();
     auto* start_of_name = bufptr;
     u32 address = 0;