sw64: kvm: fix incorrect page_ref_count() call

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I56WV8

--------------------------------

The last page_ref_count() call will cause kernel panic if
kvm memory pool is at the end of DRAM. This patch reorders
the checks to avoid illegal atomic_read operation.
Signed-off-by: NMin Fanlei <minfanlei@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>

arch/sw_64/kernel/setup.c

@@ -1026,8 +1026,7 @@ static int __init sw64_kvm_pool_init(void)
 	end_page  = pfn_to_page((kvm_mem_base + kvm_mem_size - 1) >> PAGE_SHIFT);
 
 	p = base_page;
-	while (page_ref_count(p) == 0 &&
-			(unsigned long)p <= (unsigned long)end_page) {
+	while (p <= end_page && page_ref_count(p) == 0) {
 		set_page_count(p, 1);
 		page_mapcount_reset(p);
 		SetPageReserved(p);