xtensa: rename prom_update_property to of_update_property

This rename happened in 79d1c71 powerpc+of: Rename the drivers/of prom_*
functions to of_*.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
xtensa: use new common dtc rule

The current rules have the .dtb files build in a different directory
from the .dts files. This patch changes xtensa to use the generic dtb
rule which builds .dtb files in the same directory as the source .dts.

This requires moving parts of arch/xtensa/boot/Makefile into newly
created arch/xtensa/boot/dts/Makefile, and updating arch/xtensa/Makefile
to call the new Makefile.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
xtensa: avoid mmap cache aliasing

Provide arch_get_unmapped_area function aligning shared memory mapping
addresses to the biggest of the page size or the cache way size. That
guarantees that corresponding virtual addresses of shared mappings are
cached by the same cache sets.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
xtensa: add finit_module syscall

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>