acpigen_ps2_keybd: Add keymap for Power key

Power key is a special non-matrixed key. Chrome /powerd
only listens to the keyboard device for this key, so add
its keymap.

BUG=b:155941390
TEST=Test that power key generates KEY_POWER in linux evtest

Change-Id: I570602d9febcb5c17e58761f2004ee88be16c27f
Signed-off-by: Rajat Jain <rajatja@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41382
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/acpi/acpigen_ps2_keybd.c

@@ -168,6 +168,8 @@ static uint32_t rest_of_keymaps[] = {
 	KEYMAP(0xd0, KEY_DOWN),
 	KEYMAP(0xcd, KEY_RIGHT),
 	KEYMAP(0xc8, KEY_UP),
+	/* Power Key */
+	KEYMAP(0xde, KEY_POWER),
 };
 
 static void ssdt_generate_physmap(struct acpi_dp *dp, uint8_t num_top_row_keys,