Fix lots of places that assume sizeof(int) == sizeof(void *). Most of

Fix lots of places that assume sizeof(int) == sizeof(void *).  Most of
these were cosmetic.  However, at least two of these changes fix bugs
where a (fake) pointer to a RX descriptor was added to the physical
memory start address with the cast in the wrong place resulting in
rxdesc[pmem_start] instead of (uintptr_t)rxdesc + pmem_start.