tpm2: tis_spi: add linux compatible fallback string

This solves a compatibility issue with Linux device trees
that contain TPMv2.x hardware. So it's easier to import DTS
from upstream kernel when migrating board init from C code
to DTS.

The issue is that fallback binding is different between Linux
and u-Boot.

Linux: "tcg,tpm_tis-spi"
U-Boot: "tis,tpm2-spi"

As there are currently no in-tree users of the U-Boot binding,
it makes sense to use Linux fallback binding.

Signed-off-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

doc/device-tree-bindings/tpm2/tis-tpm2-spi.txt

@@ -2,7 +2,7 @@ ST33TPHF20 SPI TPMv2.0 bindings
 -------------------------------
 
 Required properties:
-- compatible		: Should be "tis,tpm2-spi"
+- compatible		: Should be "tcg,tpm_tis-spi"
 - reg			: SPI Chip select
 
 Optional properties:
@@ -12,7 +12,7 @@ Optional properties:
 Example:
 
 	tpm@1 {
-		compatible = "tis,tpm2-spi";
+		compatible = "tcg,tpm_tis-spi";
 		reg = <1>;
 		spi-max-frequency = <10000000>;
 	};

drivers/tpm/tpm2_tis_spi.c

@@ -676,7 +676,7 @@ static const struct tpm_tis_chip_data tpm_tis_std_chip_data = {
 
 static const struct udevice_id tpm_tis_spi_ids[] = {
 	{
-		.compatible = "tis,tpm2-spi",
+		.compatible = "tcg,tpm_tis-spi",
 		.data = (ulong)&tpm_tis_std_chip_data,
 	},
 	{ }