cpupower: Recognise amd-pstate active mode driver

amd-pstate active mode driver name is "amd-pstate-epp". Use common
prefix for string matching condition to recognise amd-pstate active mode
driver.

Reviewed-by: Gautham R. Shenoy <[e-mail]>
Signed-off-by: Wyes Karny <[e-mail]>
Reviewed-by: Mario Limonciello <[e-mail]>
Tested-by: Perry Yuan <[e-mail]>
Acked-by: Huang Rui <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/power/cpupower/utils/helpers/misc.c

···
 	if (!driver)
 		return ret;
 
-	if (!strcmp(driver, "amd-pstate"))
+	if (!strncmp(driver, "amd", 3))
 		ret = true;
 
 	cpufreq_put_driver(driver);