CHROMIUM: spring: dts: add Atmel trackpad configuration

CHROMIUM: spring: dts: add Atmel trackpad configuration

The Cypress one is defined in the common device tree,
so we currently define both of them.

Also add another entry if the trackpad is in bootloader mode at
address 0x25.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
BUG=chrome-os-partner:17825
TEST=boot a machine with an Atmel trackpad attached and one with Cypress
trackpad and have a working pointer on both of them.

Change-Id: I1886f7d3b2eedf39d73ca31376bd3229f8373b2d
Reviewed-on: https://gerrit.chromium.org/gerrit/43230
Reviewed-by: Benson Leung <bleung@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>