Loongson3a92h: fix ls2h rtc month verify code.

Change-Id: I9a45a70aaedecbfe0ae8ccb777e1e8e97eb12d7f
Signed-off-by: QiaoChong <qiaochong@loongson.cn>

Targets/Bonito3a92h/Bonito/tgt_machdep.c

@@ -728,7 +728,7 @@ static void init_legacy_rtc(void)
 
 	year	= inl(LS2H_TOY_READ1_REG);
 	val	= inl(LS2H_TOY_READ0_REG);
-	month	= ((val >> 26) & 0x3f) - 1;
+	month	= ((val >> 26) & 0x3f);
 	date	= (val >> 21) & 0x1f;
 	hour	= (val >> 16) & 0x1f;
 	min	= (val >> 10) & 0x3f;