rtc: bd70528: Drop BD70528 support

The only known BD70528 use-cases are such that the PMIC is controlled
from separate MCU which is not running Linux. I am not aware of
any Linux driver users. Furthermore, it seems there is no demand for
this IC. Let's ease the maintenance burden and drop the driver. We can
always add it back if there is sudden need for it.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210527105819.GA3111334@localhost.localdomain

drivers/rtc/Kconfig

@@ -501,12 +501,11 @@ config RTC_DRV_M41T80_WDT
 	  watchdog timer in the ST M41T60 and M41T80 RTC chips series.
 
 config RTC_DRV_BD70528
-	tristate "ROHM BD70528, BD71815 and BD71828 PMIC RTC"
-	depends on MFD_ROHM_BD71828 || MFD_ROHM_BD70528
-	depends on BD70528_WATCHDOG || !BD70528_WATCHDOG
+	tristate "ROHM BD71815 and BD71828 PMIC RTC"
+	depends on MFD_ROHM_BD71828
 	help
 	  If you say Y here you will get support for the RTC
-	  block on ROHM BD70528, BD71815 and BD71828 Power Management IC.
+	  block on ROHM BD71815 and BD71828 Power Management IC.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-bd70528.