hp/pavilion_m6_1035dx: Add basic EC initialization

The EC is now set to ACPI mode, and properly generates SCIs on
external events. This fixes the issue where battery notifications were
not working.
The keyboard matrix type is also explicitly set up.

Change-Id: Ib6f0d23984d4ed1320340282469b8325c83547d1
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5471
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>