octeontx2-pf: Fix unintentional sign extension issue

The shifting of the u16 result from ntohs(proto) by 16 bits to the
left will be promoted to a 32 bit signed int and then sign-extended
to a u64.  In the event that the top bit of the return from ntohs(proto)
is set then all then all the upper 32 bits of a 64 bit long end up as
also being set because of the sign-extension. Fix this by casting to
a u64 long before the shift.

Addresses-Coverity: ("Unintended sign extension")
Fixes: f0c2982a ("octeontx2-pf: Add support for SR-IOV management function")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20201118130520.460365-1-colin.king@canonical.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -2084,7 +2084,7 @@ static int otx2_do_set_vf_vlan(struct otx2_nic *pf, int vf, u16 vlan, u8 qos,
 	vtag_req->vtag_size = VTAGSIZE_T4;
 	vtag_req->cfg_type = 0; /* tx vlan cfg */
 	vtag_req->tx.cfg_vtag0 = 1;
-	vtag_req->tx.vtag0 = (ntohs(proto) << 16) | vlan;
+	vtag_req->tx.vtag0 = ((u64)ntohs(proto) << 16) | vlan;
 
 	err = otx2_sync_mbox_msg(&pf->mbox);
 	if (err)