hw/tpm: Rename TPMDEV as TPM_BACKEND in Kconfig

The TPMDEV describe TPM backends. Use the TPM_BACKEND config
name which is self-explicit.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Message-id: 20200612085444.8362-4-philmd@redhat.com
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

hw/tpm/Kconfig

@@ -1,4 +1,4 @@
-config TPMDEV
+config TPM_BACKEND
     bool
     depends on TPM
 
@@ -15,26 +15,26 @@ config TPM_TIS_SYSBUS
 config TPM_TIS
     bool
     depends on TPM
-    select TPMDEV
+    select TPM_BACKEND
 
 config TPM_CRB
     bool
     depends on TPM && PC
-    select TPMDEV
+    select TPM_BACKEND
 
 config TPM_PASSTHROUGH
     bool
     default y
     # FIXME: should check for x86 host as well
-    depends on TPMDEV && LINUX
+    depends on TPM_BACKEND && LINUX
 
 config TPM_EMULATOR
     bool
     default y
-    depends on TPMDEV
+    depends on TPM_BACKEND
 
 config TPM_SPAPR
     bool
     default y
     depends on TPM && PSERIES
-    select TPMDEV
+    select TPM_BACKEND