loader: use file path size from fw_cfg.h

Avoid a bit of code duplication, make
max file path constant reusable.
Suggested-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NGerd Hoffmann <kraxel@redhat.com>
Tested-by: NGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: NIgor Mammedov <imammedo@redhat.com>
Tested-by: NIgor Mammedov <imammedo@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/core/loader.c

@@ -663,7 +663,7 @@ int rom_add_file(const char *file, const char *fw_dir,
     rom_insert(rom);
     if (rom->fw_file && fw_cfg) {
         const char *basename;
-        char fw_file_name[56];
+        char fw_file_name[FW_CFG_MAX_FILE_PATH];
         void *data;
 
         basename = strrchr(rom->fw_file, '/');

include/hw/nvram/fw_cfg.h

@@ -46,12 +46,14 @@
 
 #define FW_CFG_INVALID          0xffff
 
+#define FW_CFG_MAX_FILE_PATH    56
+
 #ifndef NO_QEMU_PROTOS
 typedef struct FWCfgFile {
     uint32_t  size;        /* file size */
     uint16_t  select;      /* write this to 0x510 to read it */
     uint16_t  reserved;
-    char      name[56];
+    char      name[FW_CFG_MAX_FILE_PATH];
 } FWCfgFile;
 
 typedef struct FWCfgFiles {