acpi: Add acpigen_write_LPI_package

Low Power Idle States defines additional information not present in the
_CST.

See ACPI Specification, Version 6.3 Section 8.4.4.3 _LPI.

BUG=b:178728116, b:185787242
TEST=Boot guybrush and dump ACPI tables

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Signed-off-by: Jason Glenesk <jason.glenesk@amd.corp-partner.google.com>
Change-Id: I4f5301b95ff8245facaf48e2fbd51cc82df2d8cc
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52529
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/include/acpi/acpi.h

@@ -898,6 +898,25 @@ typedef struct acpi_tstate {
 	u32 status;
 } __packed acpi_tstate_t;
 
+enum acpi_lpi_state_flags {
+	ACPI_LPI_STATE_DISABLED = 0,
+	ACPI_LPI_STATE_ENABLED
+};
+
+/* Low Power Idle State */
+struct acpi_lpi_state {
+	u32 min_residency_us;
+	u32 worst_case_wakeup_latency_us;
+	u32 flags;
+	u32 arch_context_lost_flags;
+	u32 residency_counter_frequency_hz;
+	u32 enabled_parent_state;
+	acpi_addr_t entry_method;
+	acpi_addr_t residency_counter_register;
+	acpi_addr_t usage_counter_register;
+	const char *state_name;
+};
+
 /* Port types for ACPI _UPC object */
 enum acpi_upc_type {
 	UPC_TYPE_A,