This switch few of the page table accessor to use the __raw variant
and does the cpu to big endian conversion of constants. This helps in
generating better code.

For ex: a pgd_none(pgd) check with and without fix is listed below

Without fix:
------------
   2240:	20 00 61 eb 	ld      r27,32(r1)
/* PGD level */
typedef struct { __be64 pgd; } pgd_t;
static inline unsigned long pgd_val(pgd_t x)
{
	return be64_to_cpu(x.pgd);

    2244:	22 00 66 78 	rldicl  r6,r3,32,32
    2248:	3e 40 7d 54 	rotlwi  r29,r3,8
    224c:	0e c0 7d 50 	rlwimi  r29,r3,24,0,7
    2250:	3e 40 c5 54 	rotlwi  r5,r6,8
    2254:	2e c4 7d 50 	rlwimi  r29,r3,24,16,23
    2258:	0e c0 c5 50 	rlwimi  r5,r6,24,0,7
    225c:	2e c4 c5 50 	rlwimi  r5,r6,24,16,23
    2260:	c6 07 bd 7b 	rldicr  r29,r29,32,31
    2264:	78 2b bd 7f 	or      r29,r29,r5
		if (pgd_none(pgd))
    2268:	00 00 bd 2f 	cmpdi   cr7,r29,0
    226c:	54 03 9e 41 	beq     cr7,25c0 <__get_user_pages_fast+0x500>

With fix:
---------
    2370:	20 00 61 eb 	ld      r27,32(r1)
		if (pgd_none(pgd))
    2374:	00 00 bd 2f 	cmpdi   cr7,r29,0
    2378:	a8 03 9e 41 	beq     cr7,2720 <__get_user_pages_fast+0x530>
			break;
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We have hugepage at the pmd level with 4K radix config. Hence we don't
need to use hugepd format with radix.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Here we create pgtable-64/4k.h and move pmd accessors that are common
between hash and radix there. We can't do much sharing with 4K Linux
page size because 4K Linux page size with hash config doesn't support
THP. So for now it is empty. In later patches we will add functions that
does conditional hash/radix accessors there.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>