x86/mm: Use proper mask when setting PUD mapping

Commit c164fbb4("x86/mm: thread pgprot_t through
init_memory_mapping()") mistakenly used __pgprot() which doesn't respect
__default_kernel_pte_mask when setting PUD mapping.

Fix it by only setting the one bit we actually need (PSE) and leaving
the other bits (that have been properly masked) alone.

Fixes: c164fbb4 ("x86/mm: thread pgprot_t through init_memory_mapping()")
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/init_64.c

@@ -645,7 +645,7 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
 			pages++;
 			spin_lock(&init_mm.page_table_lock);
 
-			prot = __pgprot(pgprot_val(prot) | __PAGE_KERNEL_LARGE);
+			prot = __pgprot(pgprot_val(prot) | _PAGE_PSE);
 
 			set_pte_init((pte_t *)pud,
 				     pfn_pte((paddr & PUD_MASK) >> PAGE_SHIFT,