arm: mach-k3: Move SYS_K3_SPL_ATF definition into R5 Kconfig

Loading ATF is only supported from the R5, move the Kconfig symbol
definition to match.

Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@foundries.io>
diff --git a/arch/arm/mach-k3/r5/Kconfig b/arch/arm/mach-k3/r5/Kconfig
index ae79f8f..317a6c4 100644
--- a/arch/arm/mach-k3/r5/Kconfig
+++ b/arch/arm/mach-k3/r5/Kconfig
@@ -43,3 +43,9 @@
 	help
 	  Offset of the combined System Firmware and configuration image tree
 	  blob to be loaded when booting from a SPI flash memory.
+
+config SYS_K3_SPL_ATF
+	bool "Start Cortex-A from SPL"
+	help
+	  Enabling this will try to start Cortex-A (typically with ATF)
+	  after SPL from R5.