[WPE] Fix build in older platforms

https://bugs.webkit.org/show_bug.cgi?id=270355

Unreviewed build fix.

The include was wrong, even if WPE_PLATFORM is not enabled,
the DMABufRendererBufferFormat definition is needed for
the empty vector.

* Source/WebKit/UIProcess/wpe/WebPageProxyWPE.cpp:

Canonical link: https://commits.webkit.org/275559@main

Source/WebKit/UIProcess/wpe/WebPageProxyWPE.cpp

@@ -36,8 +36,11 @@
 #include <wpe/wpe-platform.h>
 #endif
 
-#if USE(GBM) && ENABLE(WPE_PLATFORM)
+#if USE(GBM)
 #include "DMABufRendererBufferFormat.h"
+#endif
+
+#if USE(GBM) && ENABLE(WPE_PLATFORM)
 #include "MessageSenderInlines.h"
 #include "WebPageMessages.h"
 #endif