video: tegra: nvmap: eliminate arm_attrib_allocator dependency

video: tegra: nvmap: eliminate arm_attrib_allocator dependency

remove the dependency that nvmap has on the arm_attrib_allocator
and the lowmem in PTEs change by adding a private page allocator
utility function and calling vm_map_ram unconditionally for all
sysmem handles.

also, add Kconfig variables to allow platforms to disallow the
SYSMEM heap, and to optionally restrict the SYSMEM and IOVMM
heaps to just HIGHMEM.

Change-Id: I3dab1c7323f54a8ab3994dc672b27fd79a9057d7
Signed-off-by: Gary King <gking@nvidia.com>