remoteproc: fix OOB read via signed offset in rsc_table_for_each_entry()

In the Linux kernel, the following vulnerability has been resolved: remoteproc: fix OOB read via signed offset in rsc_table_for_each_entry() table->offset[i] is a u32 from firmware, but was stored into a signed int. A crafted offset like 0xFFFFFFF0 becomes -16, placing hdr 16 bytes before the table buffer. The subsequent avail check was bypassed because the negative int was promoted to a large size_t in the expression "table_sz - offset - sizeof(*hdr)", yielding a large positive avail and letting the out-of-bounds hdr->type read proceed undetected. Store the offset as u32 and validate it with unsigned comparisons before any pointer arithmetic.