spl: configure 'return to bootrom' separately for SPL and TPL

On the RK3368, we want our TPL to use the 'return to bootrom' boot
method (to have the bootrom load up the SPL stage) and then continue
with different boot methods (MMC, SPI, etc.) from SPL.

This adds the config option needed to control the availabily of the
'return to bootrom' boot-method separately for the TPL stage.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

common/spl/Kconfig

@@ -698,6 +698,17 @@ config TPL
 
 if TPL
 
+config TPL_BOOTROM_SUPPORT
+        bool "Support returning to the BOOTROM (from TPL)"
+	help
+	  Some platforms (e.g. the Rockchip RK3368) provide support in their
+	  ROM for loading the next boot-stage after performing basic setup
+	  from the TPL stage.
+
+	  Enable this option, to return to the BOOTROM through the
+	  BOOT_DEVICE_BOOTROM (or fall-through to the next boot device in the
+	  boot device list, if not implemented for a given board)
+
 config TPL_ENV_SUPPORT
 	bool "Support an environment"
 	help