[BUGFIX] Increase "maxitems" for media in TCA of pages

Because of type TEXT the database already allows for more
than 5 items. So this patch raises the level in TCA as well.

Change-Id: I7acb4d9bfc38b6d5cef0fabe82560586f0c4eea3
Resolves: #28317
Releases: 4.6
Reviewed-on: http://review.typo3.org/3417
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
Reviewed-by: Chris Zepernick
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter