dm: tpm: Drop CONFIG_DM_TPM

Now that all TPM drivers use driver model, we can drop the special driver
model CONFIG option.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Christophe Ricard<christophe-h.ricard@st.com>
diff --git a/lib/Kconfig b/lib/Kconfig
index a8f8460..30e84ed 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -56,6 +56,7 @@
 
 config TPM
 	bool "Trusted Platform Module (TPM) Support"
+	depends on DM
 	help
 	  This enables support for TPMs which can be used to provide security
 	  features for your board. The TPM can be connected via LPC or I2C