xen/riscv: use pte_is_valid() in pte_is_mapping()

Use pte_is_valid() instead of open-coding the PTE_VALID check.

No functional change.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Baptiste Le Duc <baptiste.le-duc@vates.tech>
Reviewed-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/riscv/include/asm/page.h

@@ -187,7 +187,7 @@ static inline bool pte_is_mapping(pte_t p)
     /* See pte_is_table() */
     ASSERT(((p.pte & PAGE_HYPERVISOR_RW) != (PTE_VALID | PTE_WRITABLE)));
 
-    return (p.pte & PTE_VALID) && (p.pte & PTE_ACCESS_MASK);
+    return pte_is_valid(p) && (p.pte & PTE_ACCESS_MASK);
 }
 
 static inline bool pte_is_superpage(pte_t p, unsigned int level)