media: mediatek: vcodec: avoid -Wcast-function-type-strict warning

The ipi handler here tries hard to maintain const-ness of its argument,
but by doing that causes a warning about function type casts:

drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c:38:32: error: cast from 'mtk_vcodec_ipi_handler' (aka 'void (*)(void *, unsigned int, void *)') to 'ipi_handler_t' (aka 'void (*)(const void *, unsigned int, void *)') converts to incompatible function type [-Werror,-Wcast-function-type-strict]
38 | ipi_handler_t handler_const = (ipi_handler_t)handler;
| ^~~~~~~~~~~~~~~~~~~~~~

Remove the hack and just use a non-const argument.

Fixes: bf1d556ad4e0 ("media: mtk-vcodec: abstract firmware interface")
Signed-off-by: Arnd Bergmann <[e-mail]>
Reviewed-by: Ricardo Ribalda <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/platform/mediatek/mdp/mtk_mdp_vpu.c

···
 	vpu->inst_addr = msg->vpu_inst_addr;
 }
 
-static void mtk_mdp_vpu_ipi_handler(const void *data, unsigned int len,
+static void mtk_mdp_vpu_ipi_handler(void *data, unsigned int len,
 				    void *priv)
 {
 	const struct mdp_ipi_comm_ack *msg = data;

drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c

···
 					   mtk_vcodec_ipi_handler handler,
 					   const char *name, void *priv)
 {
-	/*
-	 * The handler we receive takes a void * as its first argument. We
-	 * cannot change this because it needs to be passed down to the rproc
-	 * subsystem when SCP is used. VPU takes a const argument, which is
-	 * more constrained, so the conversion below is safe.
-	 */
-	ipi_handler_t handler_const = (ipi_handler_t)handler;
-
-	return vpu_ipi_register(fw->pdev, id, handler_const, name, priv);
+	return vpu_ipi_register(fw->pdev, id, handler, name, priv);
 }
 
 static int mtk_vcodec_vpu_ipi_send(struct mtk_vcodec_fw *fw, int id, void *buf,

drivers/media/platform/mediatek/vpu/mtk_vpu.c

···
 }
 EXPORT_SYMBOL_GPL(vpu_load_firmware);
 
-static void vpu_init_ipi_handler(const void *data, unsigned int len, void *priv)
+static void vpu_init_ipi_handler(void *data, unsigned int len, void *priv)
 {
 	struct mtk_vpu *vpu = priv;
 	const struct vpu_run *run = data;

drivers/media/platform/mediatek/vpu/mtk_vpu.h

···
  * VPU interfaces with other blocks by share memory and interrupt.
  */
 
-typedef void (*ipi_handler_t) (const void *data,
+typedef void (*ipi_handler_t) (void *data,
 			       unsigned int len,
 			       void *priv);