machine: add Sirivision S25G1109FP V1.3 (8x2.5G + 1xSFP+)

RTL8373 (non-N) with an RTL8224 quad 2.5G PHY, 2 MB GD25Q16ESIG flash, no PoE.
The wiring is close to the KP-9000-9XHML-X V3.1 (same 8+1 topology, same I2C on
GPIO39/40), but three things differ and were determined on hardware:

- ModAbs is GPIO30 (low with a module inserted, high with an empty cage) and LOS
  is GPIO37 (high without light), not GPIO38.  GPIO38, the ModAbs pin of the
  KP-9000 reference, is tied low on this board, which made the firmware believe a
  module was permanently inserted and retry the I2C read forever.
- The reset button is GPIO54, not GPIO48.  GPIO48 never changes here, so the
  button appeared to do nothing.
- The LED wiring follows the stock port order (pin 3n+m belongs to port n+1,
  LED function m), so the mux table is the chip default except that pin 25 --
  the SFP LED -- is driven by function 0, the only populated function in SET1.
  Per copper port the left LED shows link/activity and the right LED shows
  2.5G, matching the front panel labels.

Verified on hardware: all eight 2.5G ports at 10/100/1000/2500 Mbps, 1G and 10G
SFP modules including DDM data, both LED columns, module insert/remove and the
reset button.

machine/S25G1109FP_V1_3.h

@@ -0,0 +1,10 @@
+#ifndef _MACHINE_S25G1109FP_V1_3_H_
+#define _MACHINE_S25G1109FP_V1_3_H_
+
+/* machine_name[] in struct machine is 30 bytes -> keep this <= 29 chars */
+/* The product is sold as SR-S25G2109F; S25G1109FP is the PCB silkscreen and
+ * belongs to a different (unmanaged PoE) model that shares this PCB. */
+#define MACHINE_MODEL "Sirivision SR-S25G2109F"
+#define MACHINE_CHIPSET RTL8373
+
+#endif