cifs: turn the pages list in cifs_readdata into an array

We'll need an array to put into a smb_rqst, so convert this into an array
instead of (ab)using the lru list_head.

Signed-off-by: Jeff Layton <jlayton@redhat.com>

diff --cc fs/cifs/cifsglob.h
Simple merge

diff --cc fs/cifs/file.c
Simple merge