rtc: mediatek: enhance the description for MediaTek PMIC based RTC

Give a better description for original MediaTek RTC driver as PMIC based
RTC in order to distinguish SoC based RTC. Also turning all words with
Mediatek to MediaTek here.

Cc: Eddie Huang <eddie.huang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Acked-by: Eddie Huang <eddie.huang@mediatek.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/Kconfig

@@ -1706,14 +1706,14 @@ config RTC_DRV_MOXART
 	   will be called rtc-moxart
 
 config RTC_DRV_MT6397
-	tristate "Mediatek Real Time Clock driver"
+	tristate "MediaTek PMIC based RTC"
 	depends on MFD_MT6397 || (COMPILE_TEST && IRQ_DOMAIN)
 	help
-	  This selects the Mediatek(R) RTC driver. RTC is part of Mediatek
+	  This selects the MediaTek(R) RTC driver. RTC is part of MediaTek
 	  MT6397 PMIC. You should enable MT6397 PMIC MFD before select
-	  Mediatek(R) RTC driver.
+	  MediaTek(R) RTC driver.
 
-	  If you want to use Mediatek(R) RTC interface, select Y or M here.
+	  If you want to use MediaTek(R) RTC interface, select Y or M here.
 
 config RTC_DRV_MT7622
 	tristate "MediaTek SoC based RTC"