s390/hugetlb: add hugepages_supported define
s390/hugetlb: add hugepages_supported define

On s390 we only can enable hugepages if the underlying hardware/hypervisor
also does support this.  Common code now would assume this to be
signaled by setting HPAGE_SHIFT to 0.  But on s390, where we only
support one hugepage size, there is a link between HPAGE_SHIFT and
pageblock_order.

So instead of setting HPAGE_SHIFT to 0, we will implement the check for
the hardware capability.

Signed-off-by: Dominik Dingel <d1e5197fc3340c52389f7f33900df40c6bf98e12@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <52616596d8f5df0d597e85ab515377f92f939c68@de.ibm.com>
Cc: Heiko Carstens <8dcf0f69152f32f23184f83357a3731522e56b9c@de.ibm.com>
Cc: Christian Borntraeger <49712f635b03c16d7f4c43df70e49ec8c565813d@de.ibm.com>
Cc: Michael Holzheu <db4757c56f54651f568cc7cda79cd93c781b1605@linux.vnet.ibm.com>
Cc: Gerald Schaefer <7a67bf9a8691f9f1ca8ce9577e14c37413ea5f58@de.ibm.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs