[15/17] ramfs: Variable order page cache support

The simplest file system to use is ramfs. Add a mount parameter that specifies the page order of the pages that ramfs should use. If the order is greater than zero then disable mmap functionality. This could be removed if the VM would be changes to support faulting higher order pages but for now

[15/17] ramfs: Variable order page cache support

The simplest file system to use is ramfs. Add a mount parameter that specifies the page order of the pages that ramfs should use. If the order is greater than zero then disable mmap functionality. This could be removed if the VM would be changes to support faulting higher order pages but for now