acpigen: Add acpigen_notify

A fairly common thing in ACPI is notifying a device when some kind of
device-specific event happens; this function simplifies writing this
pattern.

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I0f18db9cc836ec9249604452f03ed9b4c6478827
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42102
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/acpi/acpigen.h

@@ -509,4 +509,7 @@ void acpigen_resource_dword(u16 res_type, u16 gen_flags, u16 type_flags,
 void acpigen_resource_qword(u16 res_type, u16 gen_flags, u16 type_flags,
 	u64 gran, u64 range_min, u64 range_max, u64 translation, u64 length);
 
+/* Emits Notify(namestr, value) */
+void acpigen_notify(const char *namestr, int value);
+
 #endif /* __ACPI_ACPIGEN_H__ */