mm: introduce __vm_normal_page()

When dealing with the speculative fault path we should use the VMA's field
cached value stored in the vm_fault structure.

Currently vm_normal_page() is using the pointer to the VMA to fetch the
vm_flags value. This patch provides a new __vm_normal_page() which is
receiving the vm_flags flags value as parameter.

Note: The speculative path is turned on for architecture providing support
for special PTE flag. So only the first block of vm_normal_page is used
during the speculative path.

Change-Id: I0f2c4ab1212fbca449bdf6e7993dafa0d41044bc
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Patch-mainline: linux-mm @ Tue, 17 Apr 2018 16:33:21
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
[charante@codeaurora.org: trivial merge conflict fixes]
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>