pmcstat: Remove no-op -k option

Commit 53d0b9e438 ("pmc: Provide full path to modules from kernel
linker") made pmcstat's -k option have no effect, but the option was
retained for backwards compatibility (while emitting a warning that
-k is not in FreeBSD 15).

Reviewed by:	jrtc27
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D53397

usr.sbin/pmcstat/pmcstat.c

@@ -519,7 +519,7 @@ main(int argc, char **argv)
 	CPU_COPY(&rootmask, &cpumask);
 
 	while ((option = getopt(argc, argv,
-	    "ACD:EF:G:ILM:NO:P:R:S:TUWZa:c:def:gi:k:l:m:n:o:p:qr:s:t:u:vw:z:")) != -1)
+	    "ACD:EF:G:ILM:NO:P:R:S:TUWZa:c:def:gi:l:m:n:o:p:qr:s:t:u:vw:z:")) != -1)
 		switch (option) {
 		case 'A':
 			args.pa_flags |= FLAG_SKIP_TOP_FN_RES;
@@ -607,11 +607,6 @@ main(int argc, char **argv)
 			args.pa_flags |= FLAG_SHOW_OFFSET;
 			break;
 
-		case 'k':	/* pathname to the kernel */
-			warnx("WARNING: -k is obsolete, has no effect "
-			    "and will be removed in FreeBSD 15.");
-			break;
-
 		case 'L':
 			do_listcounters = 1;
 			break;