spi: octeon_spi: Use a fixed 100MHz input clock on Octeon TX2

Octeon TX2 sets the TB100_EN bit in the config register. We need to use
a fixed 100MHz clock for this as well to work properly.
Signed-off-by: NStefan Roese <sr@denx.de>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Suneel Garapati <sgarapati@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Jagan Teki <jagan@amarulasolutions.com>

drivers/spi/octeon_spi.c

@@ -519,7 +519,10 @@ static int octeon_spi_set_speed(struct udevice *bus, uint max_hz)
 	if (max_hz > OCTEON_SPI_MAX_CLOCK_HZ)
 		max_hz = OCTEON_SPI_MAX_CLOCK_HZ;
 
-	clk_rate = clk_get_rate(&priv->clk);
+	if (device_is_compatible(bus, "cavium,thunderx-spi"))
+		clk_rate = 100000000;
+	else
+		clk_rate = clk_get_rate(&priv->clk);
 	if (IS_ERR_VALUE(clk_rate))
 		return -EINVAL;