mb/siemens/mc_ehl: Move RTC Kconfig option to variant level

With a redesign of mc_ehl2 the used RTC was changed. In order to be able
to select a different RTC type for every variant move the RTC Kconfig
switch into the variant's Kconfig file.

Change-Id: Ia24703ede6a935e3b9886df87237857baec7d6a0
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67100
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/siemens/mc_ehl/Kconfig

@@ -5,7 +5,6 @@ config BOARD_SIEMENS_BASEBOARD_MC_EHL
 	select DRIVERS_I2C_GENERIC
 	select HAVE_SPD_IN_CBFS
 	select HAVE_ACPI_TABLES
-	select DRIVERS_I2C_RX6110SA
 	select DRIVER_SIEMENS_NC_FPGA
 	select NC_FPGA_NOTIFY_CB_READY
 	select MAINBOARD_HAS_TPM2

src/mainboard/siemens/mc_ehl/variants/mc_ehl1/Kconfig

@@ -2,6 +2,7 @@ if BOARD_SIEMENS_MC_EHL1
 
 config BOARD_SPECIFIC_OPTIONS
 	def_bool y
+	select DRIVERS_I2C_RX6110SA
 	select DRIVER_INTEL_I210
 	select INTEL_LPSS_UART_FOR_CONSOLE
 	select NC_FPGA_POST_CODE

src/mainboard/siemens/mc_ehl/variants/mc_ehl2/Kconfig

@@ -2,6 +2,7 @@ if BOARD_SIEMENS_MC_EHL2
 
 config BOARD_SPECIFIC_OPTIONS
 	def_bool y
+	select DRIVERS_I2C_RX6110SA
 	select DRIVER_INTEL_I210
 	select SOC_INTEL_COMMON_BLOCK_LPC_COMB_ENABLE
 	select EHL_TSN_DRIVER