tracing: Use ? : shortcut in trace macros

Instead of having:

  #define __assign_str(dst, src)					\
	memcpy(__get_str(dst), __data_offsets.dst##_ptr_ ?		\
		__data_offsets.dst##_ptr_ : "(null)",			\
		__get_dynamic_array_len(dst))

Use the ? : shortcut and compact it down to:

  #define __assign_str(dst, src)					\
	memcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? : "(null)",	\
	       __get_dynamic_array_len(dst))

Link: https://lore.kernel.org/linux-trace-kernel/20240222211442.949327725@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>