rambi: Add _PRW for LID0 ACPI Device

The kernel will not track wakeup events for devices unless they have
a defined _PRW.  There is no EC output of the lid signal coming to
a GPIO and instead it pulses PCH_WAKE#.

BUG=chrome-os-partner:27631
TEST=Manual on Rambi.
- Run lidclose + lidopen on EC console, verify that wakeup_count
  increments.
- Run lidclose + lidopen in rapid succession, verify that suspend
  request is aborted.
BRANCH=Rambi.

Change-Id: I8d4c58a7bb37d7e474ec094fe96e46e1bfd980de
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/200289
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/mainboard/google/rambi/acpi/mainboard.asl

@@ -26,6 +26,7 @@ Scope (\_SB)
 	Device (LID0)
 	{
 		Name (_HID, EisaId ("PNP0C0D"))
+		Name (_PRW, Package() { BOARD_PCH_WAKE_GPIO, 0x5 })
 		Method (_LID, 0)
 		{
 			Store (\_SB.PCI0.LPCB.EC0.LIDS, \LIDS)

src/mainboard/google/rambi/onboard.h

@@ -22,6 +22,9 @@
 
 #include "irqroute.h"
 
+/* PCH wake signal from EC. */
+#define BOARD_PCH_WAKE_GPIO             ACPI_ENABLE_WAKE_SUS_GPIO(0)
+
 #define BOARD_TRACKPAD_NAME             "trackpad"
 #define BOARD_TRACKPAD_IRQ              GPIO_S0_DED_IRQ(TPAD_IRQ_OFFSET)
 #define BOARD_TRACKPAD_WAKE_GPIO        ACPI_ENABLE_WAKE_SUS_GPIO(1)