ARM: keystone2: K2G: Add support for different arm/device speeds

The maximum device and arm speeds can be determined by reading
EFUSE_BOOTROM register. As there is already a framework for reading this
register, adding support for all possible speeds on k2g devices.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-keystone/clock.c b/arch/arm/mach-keystone/clock.c
index 1ae3baf..b25db1e 100644
--- a/arch/arm/mach-keystone/clock.c
+++ b/arch/arm/mach-keystone/clock.c
@@ -238,8 +238,11 @@
 			return spds[speed];
 	}
 
-	/* If no bit is set, use SPD800 */
-	return SPD800;
+	/* If no bit is set, return minimum speed */
+	if (cpu_is_k2g())
+		return SPD200;
+	else
+		return SPD800;
 }
 
 static inline u32 read_efuse_bootrom(void)