Fix wrong reference to READ_ONCE and WRITE_ONCE macro (#1)

The original 'include/linux/compiler.h' does not contain the definition                                                                                       
of READ_ONCE and WRITE_ONCE macro. This commit replaces reference with
the one to 'include/asm-generic/rwonce.h'.

Author: idoleat

concurrency-primer.tex

@@ -1270,7 +1270,7 @@ \section{Atomic fusion}
 macros for this exact purpose.\punckern\footnote{See
 \href{https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4374.html}{\textsc{n}4374}
 and the kernel's
-\href{https://elixir.bootlin.com/linux/latest/source/include/linux/compiler.h}{\texttt{compiler.h}} for details.}
+\href{https://elixir.bootlin.com/linux/latest/source/include/asm-generic/rwonce.h}{\texttt{rwonce.h}} for details.}
 
 \section{Takeaways}