mm: remove __HAVE_ARCH_PTEP_CLEAR in pgtable.h

Currently, there is no architecture definition __HAVE_ARCH_PTEP_CLEAR,
Generic ptep_clear() is the only definition for all architecture, So drop
the "#ifndef __HAVE_ARCH_PTEP_CLEAR".

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Tong Tiangen <[email protected]>
Suggested-by: Anshuman Khandual <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Tong Tiangen

include/linux/pgtable.h

@@ -272,13 +272,11 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 }
 #endif
 
-#ifndef __HAVE_ARCH_PTEP_CLEAR
 static inline void ptep_clear(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep)
 {
 	ptep_get_and_clear(mm, addr, ptep);
 }
-#endif
 
 #ifndef __HAVE_ARCH_PTEP_GET
 static inline pte_t ptep_get(pte_t *ptep)