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/plot_dram/PlotPowerStates.py

@@ -295,7 +295,7 @@ def plotStackedStates(delay, states_list, bottom_state, plot_name, ylabel_str):
                 for prev_sum, new_s in zip(time_sum, l_states[state])
             ]
 
-        ax[sub_idx].set_title("Bank util %s" % bank_util)
+        ax[sub_idx].set_title(f"Bank util {bank_util}")
         ax[sub_idx].xaxis.set_ticks(ind + width / 2.0)
         ax[sub_idx].xaxis.set_ticklabels(seqBytesValues, rotation=45)
         ax[sub_idx].set_xlabel("Seq. bytes")

util/plot_dram/dram_sweep_plot.py

@@ -147,7 +147,7 @@ def main():
             # avg_pwr is in mW, peak_bw in MiByte/s, bus_util in percent
             z.append(avg_pwr[j] / (bus_util[j] / 100.0 * peak_bw[j] / 1000.0))
         else:
-            print("Unexpected mode %s" % mode)
+            print(f"Unexpected mode {mode}")
             exit(-1)
 
         i += 1

util/plot_dram/lowp_dram_sweep_plot.py

@@ -76,7 +76,7 @@ parser.add_argument("--pdf", action="store_true", help="output Latex and pdf")
 def main():
     args = parser.parse_args()
     if not os.path.isfile(args.statsfile):
-        exit("Error! File not found: %s" % args.statsfile)
+        exit(f"Error! File not found: {args.statsfile}")
     if not os.path.isdir(args.outdir):
         os.mkdir(args.outdir)