octeontx2-pf: remove unused variables req_hdr and rsp_hdr

Clang static checker(scan-buid):
drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c:503:2: warning:
Value stored to 'rsp_hdr' is never read [deadcode.DeadStores]

Remove these unused variables to save some space.
Signed-off-by: Su Hui <suhui@nfschina.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240328020723.4071539-1-suhui@nfschina.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c

@@ -450,7 +450,6 @@ static void otx2_pfvf_mbox_handler(struct work_struct *work)
 	struct mbox_msghdr *msg = NULL;
 	int offset, vf_idx, id, err;
 	struct otx2_mbox_dev *mdev;
-	struct mbox_hdr *req_hdr;
 	struct otx2_mbox *mbox;
 	struct mbox *vf_mbox;
 	struct otx2_nic *pf;
@@ -461,9 +460,8 @@ static void otx2_pfvf_mbox_handler(struct work_struct *work)
 
 	mbox = &pf->mbox_pfvf[0].mbox;
 	mdev = &mbox->dev[vf_idx];
-	req_hdr = (struct mbox_hdr *)(mdev->mbase + mbox->rx_start);
 
-	offset = ALIGN(sizeof(*req_hdr), MBOX_MSG_ALIGN);
+	offset = ALIGN(sizeof(struct mbox_hdr), MBOX_MSG_ALIGN);
 
 	for (id = 0; id < vf_mbox->num_msgs; id++) {
 		msg = (struct mbox_msghdr *)(mdev->mbase + mbox->rx_start +
@@ -494,7 +492,6 @@ static void otx2_pfvf_mbox_up_handler(struct work_struct *work)
 	struct otx2_nic *pf = vf_mbox->pfvf;
 	struct otx2_mbox_dev *mdev;
 	int offset, id, vf_idx = 0;
-	struct mbox_hdr *rsp_hdr;
 	struct mbox_msghdr *msg;
 	struct otx2_mbox *mbox;
 
@@ -502,8 +499,7 @@ static void otx2_pfvf_mbox_up_handler(struct work_struct *work)
 	mbox = &pf->mbox_pfvf[0].mbox_up;
 	mdev = &mbox->dev[vf_idx];
 
-	rsp_hdr = (struct mbox_hdr *)(mdev->mbase + mbox->rx_start);
-	offset = mbox->rx_start + ALIGN(sizeof(*rsp_hdr), MBOX_MSG_ALIGN);
+	offset = mbox->rx_start + ALIGN(sizeof(struct mbox_hdr), MBOX_MSG_ALIGN);
 
 	for (id = 0; id < vf_mbox->up_num_msgs; id++) {
 		msg = mdev->mbase + offset;