bios_table: Relax pldm_bios_table_string_entry_decode_string_check()

Allow the string decoded by
pldm_bios_table_string_entry_decode_string_check() to be truncated, as
per the unchecked pldm_bios_table_string_entry_decode_string(). With
this change pldm_bios_table_string_entry_decode_string_check() provides
assert() safety but is otherwise equivalent.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Ia872f1496c642efbb34ee3ae29455f4eaf574082
diff --git a/src/bios_table.c b/src/bios_table.c
index 436f3e6..d6cf6f3 100644
--- a/src/bios_table.c
+++ b/src/bios_table.c
@@ -114,9 +114,9 @@
 {
 	POINTER_CHECK(entry);
 	POINTER_CHECK(buffer);
-	size_t length =
-		pldm_bios_table_string_entry_decode_string_length(entry);
-	BUFFER_SIZE_EXPECT(size, length + 1);
+	if (size == 0) {
+		return PLDM_ERROR_INVALID_LENGTH;
+	}
 	pldm_bios_table_string_entry_decode_string(entry, buffer, size);
 	return PLDM_SUCCESS;
 }