arm: mvebu: turris_omnia: Move SPL's SYS_MALLOC_SIMPLE to Kconfig

Instead of declaring CONFIG_SYS_MALLOC_SIMPLE dependant on
CONFIG_SPL_BUILD in board config header, select
CONFIG_SPL_SYS_MALLOC_SIMPLE in Kconfig.

Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
index 54dff99..8365305 100644
--- a/arch/arm/mach-mvebu/Kconfig
+++ b/arch/arm/mach-mvebu/Kconfig
@@ -128,6 +128,7 @@
 	select I2C_MUX
 	select I2C_MUX_PCA954x
 	select SPL_I2C_MUX
+	select SPL_SYS_MALLOC_SIMPLE
 	select SYS_I2C_MVTWSI
 	select ATSHA204A
 
diff --git a/include/configs/turris_omnia.h b/include/configs/turris_omnia.h
index 8d7d5c2..273ff85 100644
--- a/include/configs/turris_omnia.h
+++ b/include/configs/turris_omnia.h
@@ -33,10 +33,6 @@
 #define CONFIG_SPL_BSS_START_ADDR	(0x40000000 + CONFIG_SPL_SIZE)
 #define CONFIG_SPL_BSS_MAX_SIZE		(16 << 10)
 
-#ifdef CONFIG_SPL_BUILD
-#define CONFIG_SYS_MALLOC_SIMPLE
-#endif
-
 #define CONFIG_SPL_STACK		(0x40000000 + ((192 - 16) << 10))
 #define CONFIG_SPL_BOOTROM_SAVE		(CONFIG_SPL_STACK + 4)
 #define CONFIG_SPL_DRIVERS_MISC