misc: Use python f-strings for string formatting

This patch has been generated by applying flynt to the
gem5 repo (ext has been excluded)

JIRA: https://gem5.atlassian.net/browse/GEM5-831

Change-Id: I0935db6223d5426b99515959bde78e374cbadb04
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/68957
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>

util/oprofile-top.py

@@ -45,7 +45,7 @@ def category(app, sym):
     for regexp, cat in categories_re:
         if regexp.match(name):
             return cat
-    print("no match for symbol %s" % name)
+    print(f"no match for symbol {name}")
     return "other"
 
 
@@ -99,4 +99,4 @@ if showidle:
 
 for d in cats:
     if d in prof:
-        print("%s -- %5.1f%% " % (d, 100 * float(prof[d]) / float(total)))
+        print(f"{d} -- {100 * float(prof[d]) / float(total):5.1f}% ")