drivers/i2c/designware: Add 100 MHz controller base clock

There are SoCs (for instance Intel Elkhart Lake) that do use 100 MHz as
the base clock for I2C controllers. To support them properly add a
frequency setting for 100 MHz to the designware I2C controller driver.

Change-Id: I9ea11c6a41fd3758b771a416251e108cbe722769
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69304
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>

src/drivers/i2c/designware/dw_i2c.c

@@ -195,6 +195,13 @@ static const struct soc_clock {
 	int clk_speed_mhz;
 	struct freq freq;
 } soc_clocks[] = {
+	{
+		.clk_speed_mhz = 100,
+		.freq = {
+			.ticks = 100,
+			.ns = 1000,
+		},
+	},
 	{
 		.clk_speed_mhz = 120,
 		.freq = {