mvebu: cortexa72: enable ARM_ARMADA_8K_CPUFREQ

Enable the AP806's cpufreq driver. This driver is compatible with the
Armada 7K and 8K platforms.

Tested-by: Stijn Segers <foss@volatilesystems.org> (RB5009UG+S+IN)
Signed-off-by: Matthew Hagan <mnhagan88@gmail.com>

target/linux/mvebu/cortexa72/config-5.10

@@ -23,6 +23,7 @@ CONFIG_ARMADA_AP806_SYSCON=y
 CONFIG_ARMADA_AP_CP_HELPER=y
 CONFIG_ARMADA_CP110_SYSCON=y
 CONFIG_ARM_AMBA=y
+CONFIG_ARM_ARMADA_8K_CPUFREQ=y
 CONFIG_ARM_GIC_V2M=y
 CONFIG_ARM_GIC_V3=y
 CONFIG_ARM_GIC_V3_ITS=y