chromeec/ec_acpi: Convert TK_DICTATE to ps2_action_key

When support for the dictation key was added in commit f2782b8328d5
(acpigen_ps2_keybd: Add support for dictation key), I had failed to
include this portion of the change in that commit. The top row key of
`TK_DICTATE` needs to be converted to the ps2_action_key.  This commit
simply adds that mapping so that it can be translated.

BUG=b:333101631
TEST=Flash DUT that emits a scancode for a dictation key, verify that it
is mapped to KEY_DICTATE in the Linux kernel using `evtest`.

Change-Id: I1be8c0a96931cca36e6bbbfa0be7d36c4cd93768
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82274
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Caveh Jalali <caveh@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/ec/google/chromeec/ec_acpi.c

@@ -233,6 +233,7 @@ static const enum ps2_action_key ps2_enum_val[] = {
 	[TK_KBD_BKLIGHT_TOGGLE] = PS2_KEY_KBD_BKLIGHT_TOGGLE,
 	[TK_MICMUTE] = PS2_KEY_MICMUTE,
 	[TK_MENU] = PS2_KEY_MENU,
+	[TK_DICTATE] = PS2_KEY_DICTATE,
 };
 
 static void fill_ssdt_ps2_keyboard(const struct device *dev)