exec: Let flatview API take void pointer arguments

Only flatview_[read/write]_continue use a byte pointer to increment
an offset. For the users, we are only dealing with a blob buffer.
Use a void pointer argument. This will let us simplify the
address_space API in the next commit.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

include/exec/memory.h

@@ -2336,7 +2336,7 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
 MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr,
                                     MemTxAttrs attrs, uint8_t *buf, hwaddr len);
 MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
-                                   MemTxAttrs attrs, uint8_t *buf,
+                                   MemTxAttrs attrs, void *buf,
                                    hwaddr len, hwaddr addr1, hwaddr l,
                                    MemoryRegion *mr);
 void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr);