Fix broken import in pongo_helper.c

Related to alfiecg24#1

Remove unnecessary header file inclusion in `src/pongo/pongo_helper.c`.

* Remove the line `#include <sys/_types/_null.h>` at line 5 to fix compilation error on Linux.

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src/pongo/pongo_helper.c

@@ -2,7 +2,6 @@
 #include <pongo/shellcode.h>
 #include <pongo/pongo.h>
 #include <pongo/lz4/lz4hc.h>
-#include <sys/_types/_null.h>
 
 extern struct AchillesArgs args;
 
@@ -258,4 +257,4 @@ bool pongo_jailbreak(usb_handle_t *handle) {
 
     // Done
     return true;
-}
+}