ftrace: Add MAINTAINERS entries for all ftrace headers

There is currently no entry for ftrace_irq.h and ftrace_regs.h. Add a
generic entry for all *ftrace* headers to include them and prevent
overlooking future ftrace headers.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://patch.msgid.link/20260305093117.853700-1-jmarchan@redhat.com
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: jeromemarchand

MAINTAINERS

@@ -10484,7 +10484,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
 F:	Documentation/trace/ftrace*
 F:	arch/*/*/*/*ftrace*
 F:	arch/*/*/*ftrace*
-F:	include/*/ftrace.h
+F:	include/*/*ftrace*
 F:	kernel/trace/fgraph.c
 F:	kernel/trace/ftrace*
 F:	samples/ftrace