Add n_10g property in machine structure

This uint8_t field corresponds to the n_sfp field and gives the number
of 10G ports for the machine. The values can be 0, 1, 2 for known machines,
all currently supported machines do not have any 10G ports, so no
need to change any entries in machine.c

machine.h

@@ -58,6 +58,7 @@ typedef struct machine {
 	// Highest logical port number
 	uint8_t max_port;
 	uint8_t n_sfp;
+	uint8_t n_10g;
 	uint8_t log_to_phys_port[9];
 	uint8_t phys_to_log_port[9]; // Starts at 0 for port 1
 	uint8_t is_sfp[9];  // 0 for non-SFP ports 1 or 2 for the I2C port number