perf tools: Allow to use cpuinfo on LoongArch

Define these macros so that the CPU name can be displayed when running
'perf report' and 'perf timechart'.

Committer notes:

No need to have:

if (strcasestr(buf, "Model Name")) {
strlcpy(cpu_m, &buf[13], 255);
break;
} else if (strcasestr(buf, "model name")) {
strlcpy(cpu_m, &buf[13], 255);
break;
}

As the point of strcasestr() is to be case insensitive to both the
haystack and the needle, so simplify the above to just:

if (strcasestr(buf, "model name")) {
strlcpy(cpu_m, &buf[13], 255);
break;
}

Signed-off-by: Yanteng Si <[e-mail]>
Acked-by: Huacai Chen <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: https://lore.kernel.org/r/d[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/header.c

···
 #define CPUINFO_PROC	{ "Processor", }
 #elif defined(__xtensa__)
 #define CPUINFO_PROC	{ "core ID", }
+#elif defined(__loongarch__)
+#define CPUINFO_PROC	{ "Model Name", }
 #else
 #define CPUINFO_PROC	{ "model name", }
 #endif

tools/perf/util/svghelper.c

···
 	file = fopen("/proc/cpuinfo", "r");
 	if (file) {
 		while (fgets(buf, 255, file)) {
-			if (strstr(buf, "model name")) {
+			if (strcasestr(buf, "model name")) {
 				strlcpy(cpu_m, &buf[13], 255);
 				break;
 			}