firmware: qemu_fw_cfg.c: potential unintialized variable

It acpi_acquire_global_lock() return AE_NOT_CONFIGURED then "glk" isn't
initialized, which, if you got very unlucky, could cause a bug.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/firmware/qemu_fw_cfg.c

@@ -77,7 +77,7 @@ static inline u16 fw_cfg_sel_endianness(u16 key)
 static inline void fw_cfg_read_blob(u16 key,
 				    void *buf, loff_t pos, size_t count)
 {
-	u32 glk;
+	u32 glk = -1U;
 	acpi_status status;
 
 	/* If we have ACPI, ensure mutual exclusion against any potential