fw_cfg: don't use reserved _ prefix

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/fw_cfg.h b/hw/fw_cfg.h
index c1019d0..4d13a4f 100644
--- a/hw/fw_cfg.h
+++ b/hw/fw_cfg.h
@@ -53,7 +53,7 @@
 
 typedef void (*FWCfgCallback)(void *opaque, uint8_t *data);
 
-typedef struct _FWCfgState FWCfgState;
+typedef struct FWCfgState FWCfgState;
 int fw_cfg_add_bytes(FWCfgState *s, uint16_t key, uint8_t *data, uint32_t len);
 int fw_cfg_add_i16(FWCfgState *s, uint16_t key, uint16_t value);
 int fw_cfg_add_i32(FWCfgState *s, uint16_t key, uint32_t value);