rtc: rx8025: drop non-DM support

A search of the tree showed there is only one user
of this driver (soon to be two) - board/socrates

The second user will be the Traverse Ten64 board.

Both these boards have DM_RTC.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index b6692e6..71777cd 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -136,6 +136,7 @@
 
 config RTC_RX8025
 	bool "Enable RX8025 driver"
+	depends on DM_RTC
 	help
 	  Support for Epson RX8025 Real Time Clock devices.