[PATCH] LoongArch: Use __pmd() helper for __swp_entry_to_pmd()

[WangYuli]

From: WangYuli <wangyl5933@xxxxxxxxxxxxxx>

The __pmd() helper macro provides the correct initialization syntax
and abstraction for the pmd_t type.

Fix follow warning on gcc-15 under specific configs [1] :

  In file included from ./include/linux/pgtable.h:6,
                   from ./include/linux/mm.h:31,
                   from ./include/linux/pagemap.h:8,
                   from arch/loongarch/mm/init.c:14:
  ./include/linux/swapops.h: In function ‘swp_entry_to_pmd’:
  ./arch/loongarch/include/asm/pgtable.h:302:34: error: missing braces around initializer [-Werror=missing-braces]
    302 | #define __swp_entry_to_pmd(x)   ((pmd_t) { (x).val | _PAGE_HUGE })
        |                                  ^
  ./include/linux/swapops.h:559:16: note: in expansion of macro ‘__swp_entry_to_pmd’
    559 |         return __swp_entry_to_pmd(arch_entry);
        |                ^~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

[1]. https://download.01.org/0day-ci/archive/20251119/202511190316.luI90kAo-lkp@xxxxxxxxx/config

Signed-off-by: WangYuli <wangyl5933@xxxxxxxxxxxxxx>
---
 arch/loongarch/include/asm/pgtable.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index 03fb60432fde..4e09f7e8bbec 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -299,7 +299,7 @@ static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
 #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(x)	((pte_t) { (x).val })
 #define __pmd_to_swp_entry(pmd) ((swp_entry_t) { pmd_val(pmd) })
-#define __swp_entry_to_pmd(x)	((pmd_t) { (x).val | _PAGE_HUGE })
+#define __swp_entry_to_pmd(x)	__pmd((x).val | _PAGE_HUGE)
 
 static inline bool pte_swp_exclusive(pte_t pte)
 {
-- 
2.51.0