max80: change esp_ctr debug signal to 4 Hz

fpga/max80.sv

@@ -834,7 +834,7 @@ module max80 (
 	.irq	( iodev_irq_esp )
 	);
 `else // !`ifdef REALLY_ESP32
-   reg [5:0] esp_ctr;
+   reg [5:-13] esp_ctr;		// 32768 * 2^-13 = 4 Hz
 
    always @(posedge ctr_32khz)
      esp_ctr <= esp_ctr + 1'b1;