Some kernel configuration options required for systemd
support are missing in davinci_all_defconfig. Add them.

This is based on recommendations in:

    http://cgit.freedesktop.org/systemd/systemd/tree/README

Options which kernel enables by default (and will thus be removed
upon next savedefconfig update) are not included.

Tested on OMAP-L138 LCDK board with fully up to date armv5
archlinux filesystem.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>