ptrace: Report error in PT_PEEK via errno

The syscall wrapper for ptrace needs to return the peeked value when
using  PT_PEEK.
Because of this, the user has to check errno to detect an error in
PT_PEEK.

This commit changes the actual syscall's interface (only for PT_PEEK) to
allow the syscall wrapper to detect an error and change errno.

Kernel/Syscall.h

@@ -432,6 +432,11 @@ struct SC_ptrace_params {
     int data;
 };
 
+struct SC_ptrace_peek_params {
+    u32* address;
+    u32* out_data;
+};
+
 void initialize();
 int sync();