soc/amd/picasso: Set I2C clock reference to 150MHz

Picasso uses a 150MHz reference clock for the Designware I2C devices.
This update allows us to get the correct speeds out.

BUG=b:143885765
TEST=Trembyle has 400kHz I2C clock

Change-Id: Ia888a74e51201b6c911e0e810f0535403204cf60
Signed-off-by: Martin Roth <martinroth@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1970656
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39589
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/amd/picasso/Kconfig

@@ -196,7 +196,7 @@ config RO_REGION_ONLY
 
 config DRIVERS_I2C_DESIGNWARE_CLOCK_MHZ
 	int
-	default 133
+	default 150
 
 config PICASSO_LPC_IOMUX
 	bool