clang-tidy: Fix clang-diagnostic-strict-prototypes diagnostics

Produces output such as:

```
/usr/bin/clang-tidy -checks=-*, bugprone-branch-clone -export-fixes /tmp/tmpjjns4w4i/tmp2vh08b10.yaml -p=build /mnt/host/andrew/src/openbmc/libpldm/src/platform.c
/mnt/host/andrew/src/openbmc/libpldm/build/../include/libpldm/pdr.h:35:24: error: a function declaration without a prototype is deprecated in all versions of C [clang-diagnostic-strict-prototypes]
pldm_pdr *pldm_pdr_init();
                       ^
                        void
```

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Ib9b679682cc25b8c1b294d2be856031f77d755d9
diff --git a/include/libpldm/pdr.h b/include/libpldm/pdr.h
index 671b726..09b376a 100644
--- a/include/libpldm/pdr.h
+++ b/include/libpldm/pdr.h
@@ -32,7 +32,7 @@
  *  for PDRs received by other entities) and can associate the returned handle
  *  to a PLDM terminus id.
  */
-pldm_pdr *pldm_pdr_init();
+pldm_pdr *pldm_pdr_init(void);
 
 /** @brief Destroy a PDR repository (and free up associated resources)
  *
@@ -239,7 +239,7 @@
  *  @return opaque pointer that acts as a handle to the tree; NULL if no
  *  tree could be created
  */
-pldm_entity_association_tree *pldm_entity_association_tree_init();
+pldm_entity_association_tree *pldm_entity_association_tree_init(void);
 
 /** @brief Add an entity into the entity association tree
  *