modified struct to fix "negative shift"

The member of width in struct e820_entries,can be declared to
uint32_t(the range of the member is bigger than 0) to avoid
negative shift.

Signed-off-by: Huihuang Shi <huihuang.shi@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/arch/x86/guest/guest.c

@@ -18,7 +18,7 @@ struct e820_mem_params e820_mem;
 struct page_walk_info {
 	uint64_t top_entry;	/* Top level paging structure entry */
 	int level;
-	int width;
+	uint32_t width;
 	bool is_user_mode;
 	bool is_write_access;
 	bool is_inst_fetch;