arm: mvebu: a38x: Detect CONFIG_SYS_TCLK from SAR register

Bit 15 in SAR register specifies if TCLK is running at 200 MHz or 250 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>
8 files changed