selftests/proc: fix string literal warning in proc-maps-race.c

This change resolves non literal string format warning invoked for
proc-maps-race.c while compiling.

proc-maps-race.c:205:17: warning: format not a string literal and no format arguments [-Wformat-security]
205 | printf(text);
| ^~~~~~
proc-maps-race.c:209:17: warning: format not a string literal and no format arguments [-Wformat-security]
209 | printf(text);
| ^~~~~~
proc-maps-race.c: In function `print_last_lines':
proc-maps-race.c:224:9: warning: format not a string literal and no format arguments [-Wformat-security]
224 | printf(start);
| ^~~~~~

Add string format specifier %s for the printf calls in both
print_first_lines() and print_last_lines() thus resolving the warnings.

The test executes fine after this change thus causing no effect to the
functional behavior of the test.

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: aadc099c480f ("selftests/proc: add verbose mode for /proc/pid/maps tearing tests")
Signed-off-by: Sukrut Heroorkar <[e-mail]>
Acked-by: Suren Baghdasaryan <[e-mail]>
Cc: David Hunter <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/proc/proc-maps-race.c

···
 		int offs = end - text;
 
 		text[offs] = '\0';
-		printf(text);
+		printf("%s", text);
 		text[offs] = '\n';
 		printf("\n");
 	} else {
-		printf(text);
+		printf("%s", text);
 	}
 }
 
···
 		nr--;
 		start--;
 	}
-	printf(start);
+	printf("%s", start);
 }
 
 static void print_boundaries(const char *title, FIXTURE_DATA(proc_maps_race) *self)