Revert "Enable KSTACK_LARGE_PAGE."

This reverts commit ca42a455f53bfd3b1a220eb84f4d61af0bb19178.
Revert "Add option to double the kernel thread stack by using larger page size."

This reverts commit 43815d7d92282ea22c0c93c5a99154251d215f60.
Revert "Move the machine dependent code parts out of vm_thread_new()."

This reverts commit c29936b768ae22095c34eb605ca34e98224610fc.
Revert "Probe and report page sizes supported by MIPS hardware."

This reverts commit 64736182a0b3d00b9603a20d873e0c85221853e4.
Revert "Back out 8db8037 in preparation for switching to a single 16K page."

This reverts commit 6d37b65380a31062fa9686e8ef93449ac379eaea.