backends: Add TPM files into their own directory

As we will have various TPM backend files, it is cleaner
to use a single directory.

Suggested-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Message-id: 20200612085444.8362-3-philmd@redhat.com
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

MAINTAINERS

@@ -2395,7 +2395,7 @@ F: hw/tpm/*
 F: include/hw/acpi/tpm.h
 F: include/sysemu/tpm*
 F: qapi/tpm.json
-F: backends/tpm.c
+F: backends/tpm/
 F: tests/qtest/*tpm*
 T: git https://github.com/stefanberger/qemu-tpm.git tpm-next
 

backends/Makefile.objs

@@ -1,7 +1,7 @@
 common-obj-y += rng.o rng-egd.o rng-builtin.o
 common-obj-$(CONFIG_POSIX) += rng-random.o
 
-common-obj-$(CONFIG_TPM) += tpm.o
+common-obj-$(CONFIG_TPM) += tpm/
 
 common-obj-y += hostmem.o hostmem-ram.o
 common-obj-$(CONFIG_POSIX) += hostmem-file.o

backends/tpm/Makefile.objs

@@ -0,0 +1 @@
+common-obj-y += tpm_backend.o