octeontx2-af: cn10k: restrict VF LMTLINE sharing to its own PF

In the Linux kernel, the following vulnerability has been resolved: octeontx2-af: cn10k: restrict VF LMTLINE sharing to its own PF rvu_mbox_handler_lmtst_tbl_setup() uses req->base_pcifunc as a direct index into the LMT map table to read another function's LMTLINE physical base address and copy it into the caller's own LMT map table entry. The mailbox dispatcher authenticates req->hdr.pcifunc from the IRQ source, but req->base_pcifunc is a separate payload field and is not sanitized. Reject the request with -EPERM when a VF caller's base_pcifunc is not a valid function under its own PF. is_pf_func_valid() bounds the FUNC field to the PF's configured VF count, keeping the computed index inside the caller's own slot block.