b43legacy: Fix -Wcast-function-type

correct usage prototype of callback in tasklet_init().
Report by https://github.com/KSPP/linux/issues/20Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Phong Tran <tranmanphong@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/b43legacy/main.c

@@ -1275,8 +1275,9 @@ static void handle_irq_ucode_debug(struct b43legacy_wldev *dev)
 }
 
 /* Interrupt handler bottom-half */
-static void b43legacy_interrupt_tasklet(struct b43legacy_wldev *dev)
+static void b43legacy_interrupt_tasklet(unsigned long data)
 {
+	struct b43legacy_wldev *dev = (struct b43legacy_wldev *)data;
 	u32 reason;
 	u32 dma_reason[ARRAY_SIZE(dev->dma_reason)];
 	u32 merged_dma_reason = 0;
@@ -3741,7 +3742,7 @@ static int b43legacy_one_core_attach(struct ssb_device *dev,
 	b43legacy_set_status(wldev, B43legacy_STAT_UNINIT);
 	wldev->bad_frames_preempt = modparam_bad_frames_preempt;
 	tasklet_init(&wldev->isr_tasklet,
-		     (void (*)(unsigned long))b43legacy_interrupt_tasklet,
+		     b43legacy_interrupt_tasklet,
 		     (unsigned long)wldev);
 	if (modparam_pio)
 		wldev->__using_pio = true;