update AMD powerflags comments

from http://www.flounder.com/cpuid80000007amd.gif
and http://support.amd.com/us/Embedded_TechDocs/25481.pdf

Signed-off-by: Thorsten Glaser <t.glaser@tarent.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

arch/x86/kernel/cpu/powerflags.c

@@ -11,10 +11,10 @@ const char *const x86_power_flags[32] = {
 	"fid",  /* frequency id control */
 	"vid",  /* voltage id control */
 	"ttp",  /* thermal trip */
-	"tm",
-	"stc",
-	"100mhzsteps",
-	"hwpstate",
+	"tm",	/* hardware thermal control */
+	"stc",	/* software thermal control */
+	"100mhzsteps", /* 100 MHz multiplier control */
+	"hwpstate", /* hardware P-state control */
 	"",	/* tsc invariant mapped to constant_tsc */
 	"cpb",  /* core performance boost */
 	"eff_freq_ro", /* Readonly aperf/mperf */