Revert "highmem: drop the patches that give ATOMIC_IOMAP on RT=y HIGHMEM=y"

This reverts commit 9f873f8a85ad378e039d4aeb16a87744df8306b8.

While dropping these patches was the right thing for fixing
the sporadic boot failues on x86-32 highmem ata_piix, it also
breaks i915 gfx driver since it fails to init if it tries to
map a giant chunk of address space all at once (as per what
happens w/o ATOMIC_IOMAP).

Needs revisiting and more thought for a final solution.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>