arm: mvebu: Support for 98DX25xx/98DX35xx SoC

Add support for the Allecat5/Alleycat5X SoC. These are L3 switches with
an integrated CPU (referred to as the CnM block in Marvell's
documentation). These have dual ARMv8.2 CPUs (Cortex-A55). This support
has been ported from Marvell's SDK which is based on a much older
version of U-Boot.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
index fe6b785..e2c98df 100644
--- a/arch/arm/mach-mvebu/Kconfig
+++ b/arch/arm/mach-mvebu/Kconfig
@@ -50,6 +50,10 @@
 	bool
 	select ARM64
 
+config ALLEYCAT_5
+	bool
+	select ARM64
+
 # Armada PLL frequency (used for NAND clock generation)
 config SYS_MVEBU_PLL_CLOCK
 	int