mvebu: consolidate SPL boot device config symbols

Use MVEBU_SPL_BOOT_DEVICE_* to select between SPI and MMC, instead of
board specific symbols. This commit enables the boot device selection
menu to all mvebu platforms, but it is only effective on Turris Omnia
and gdsys Controlcenter DC platforms. A following commit will enable
boot selection for other platforms.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/include/configs/turris_omnia.h b/include/configs/turris_omnia.h
index 9d4d0df..44d5016 100644
--- a/include/configs/turris_omnia.h
+++ b/include/configs/turris_omnia.h
@@ -93,13 +93,13 @@
 #define CONFIG_SPL_BOOTROM_SAVE		(CONFIG_SPL_STACK + 4)
 #define CONFIG_SPL_DRIVERS_MISC_SUPPORT
 
-#ifdef CONFIG_TURRIS_OMNIA_SPL_BOOT_DEVICE_SPI
+#ifdef CONFIG_MVEBU_SPL_BOOT_DEVICE_SPI
 /* SPL related SPI defines */
 # define CONFIG_SYS_SPI_U_BOOT_OFFS	0x24000
 # define CONFIG_SYS_U_BOOT_OFFS		CONFIG_SYS_SPI_U_BOOT_OFFS
 #endif
 
-#ifdef CONFIG_TURRIS_OMNIA_SPL_BOOT_DEVICE_MMC
+#ifdef CONFIG_MVEBU_SPL_BOOT_DEVICE_MMC
 /* SPL related MMC defines */
 # define CONFIG_SYS_MMC_U_BOOT_OFFS		(160 << 10)
 # define CONFIG_SYS_U_BOOT_OFFS			CONFIG_SYS_MMC_U_BOOT_OFFS