arm: mvebu: a37x: Detect CONFIG_SYS_TCLK from SAR register

Bit 20 in SAR register specifies if TCLK is running at 200 MHz or 166 MHz.
Use this information instead of manual configuration in every board file.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/mach-mvebu/include/mach/soc.h b/arch/arm/mach-mvebu/include/mach/soc.h
index cb323aa..eb6906a 100644
--- a/arch/arm/mach-mvebu/include/mach/soc.h
+++ b/arch/arm/mach-mvebu/include/mach/soc.h
@@ -145,6 +145,9 @@
 
 #define BOOT_FROM_UART		0x30
 #define BOOT_FROM_SPI		0x38
+
+#define CONFIG_SYS_TCLK		((readl(CONFIG_SAR_REG) & BIT(20)) ? \
+				 200000000 : 166000000)
 #elif defined(CONFIG_ARMADA_38X)
 /* SAR values for Armada 38x */
 #define CONFIG_SAR_REG		(MVEBU_REGISTER(0x18600))