cpu_ioreq_pio, cpu_ioreq_move: i should be uint32_t rather than int

The current code compare i (int) with req->count (uint32_t) in a for
loop, risking an infinite loop if req->count is equal to UINT_MAX.

Also i is only used in comparisons or multiplications with unsigned
integers.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Dongxiao Xu <dongxiao.xu@intel.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NIan Jackson <ian.jackson@eu.citrix.com>

xen-all.c

@@ -721,7 +721,7 @@ static inline void write_phys_req_item(hwaddr addr,
 
 static void cpu_ioreq_pio(ioreq_t *req)
 {
-    int i;
+    uint32_t i;
 
     if (req->dir == IOREQ_READ) {
         if (!req->data_is_ptr) {
@@ -750,7 +750,7 @@ static void cpu_ioreq_pio(ioreq_t *req)
 
 static void cpu_ioreq_move(ioreq_t *req)
 {
-    int i;
+    uint32_t i;
 
     if (!req->data_is_ptr) {
         if (req->dir == IOREQ_READ) {