objtool: Add vpanic() to the noreturn list

vpanic() does not return. However, objtool doesn't know this and gets
confused:
kernel/trace/rv/reactor_panic.o: warning: objtool: rv_panic_reaction(): unexpected end of section .text

Add vpanic() to the list of noreturn functions.

Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/073f826ebec18b2bb59cba88606cd865d8039fd2.1752232374.git.namcao@linutronix.de


Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507110826.2ekbVdWZ-lkp@intel.com/


Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>