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/src/bios_table.c b/src/bios_table.c
index d7735e1..ef69dc2 100644
--- a/src/bios_table.c
+++ b/src/bios_table.c
@@ -35,7 +35,7 @@
 		*errmsg = msg;
 }
 
-static uint16_t get_bios_string_handle()
+static uint16_t get_bios_string_handle(void)
 {
 	static uint16_t handle = 0;
 	assert(handle != UINT16_MAX);
@@ -117,7 +117,7 @@
 	       pldm_bios_table_string_entry_decode_string_length(entry);
 }
 
-static uint16_t get_bios_attr_handle()
+static uint16_t get_bios_attr_handle(void)
 {
 	static uint16_t handle = 0;
 	assert(handle != UINT16_MAX);
@@ -458,7 +458,7 @@
 	uint64_t default_value;
 } __attribute__((packed));
 
-size_t pldm_bios_table_attr_entry_integer_encode_length()
+size_t pldm_bios_table_attr_entry_integer_encode_length(void)
 {
 	return sizeof(struct pldm_bios_attr_table_entry) - 1 +
 	       sizeof(struct attr_table_integer_entry_fields);
@@ -743,7 +743,7 @@
 	    str_length);
 }
 
-size_t pldm_bios_table_attr_value_entry_encode_integer_length()
+size_t pldm_bios_table_attr_value_entry_encode_integer_length(void)
 {
 	return sizeof(struct pldm_bios_attr_val_table_entry) - 1 +
 	       sizeof(uint64_t);
diff --git a/src/pdr.c b/src/pdr.c
index fe28aa9..b3a5d5a 100644
--- a/src/pdr.c
+++ b/src/pdr.c
@@ -110,7 +110,7 @@
 	return record->record_handle;
 }
 
-pldm_pdr *pldm_pdr_init()
+pldm_pdr *pldm_pdr_init(void)
 {
 	pldm_pdr *repo = malloc(sizeof(pldm_pdr));
 	assert(repo != NULL);
@@ -375,7 +375,7 @@
 	return node->entity;
 }
 
-pldm_entity_association_tree *pldm_entity_association_tree_init()
+pldm_entity_association_tree *pldm_entity_association_tree_init(void)
 {
 	pldm_entity_association_tree *tree =
 	    malloc(sizeof(pldm_entity_association_tree));
diff --git a/src/requester/pldm.c b/src/requester/pldm.c
index 34f0c30..8b9a17c 100644
--- a/src/requester/pldm.c
+++ b/src/requester/pldm.c
@@ -10,7 +10,7 @@
 
 const uint8_t MCTP_MSG_TYPE_PLDM = 1;
 
-pldm_requester_rc_t pldm_open()
+pldm_requester_rc_t pldm_open(void)
 {
 	int fd = -1;
 	int rc = -1;