riscv: sifive_u: Instantiate OTP memory with a serial number

This adds an OTP memory with a given serial number to the sifive_u
machine. With such support, the upstream U-Boot for sifive_fu540
boots out of the box on the sifive_u machine.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

include/hw/riscv/sifive_u.h

@@ -23,6 +23,7 @@
 #include "hw/riscv/riscv_hart.h"
 #include "hw/riscv/sifive_cpu.h"
 #include "hw/riscv/sifive_u_prci.h"
+#include "hw/riscv/sifive_u_otp.h"
 
 #define TYPE_RISCV_U_SOC "riscv.sifive.u.soc"
 #define RISCV_U_SOC(obj) \
@@ -39,6 +40,7 @@ typedef struct SiFiveUSoCState {
     RISCVHartArrayState u_cpus;
     DeviceState *plic;
     SiFiveUPRCIState prci;
+    SiFiveUOTPState otp;
     CadenceGEMState gem;
 } SiFiveUSoCState;
 
@@ -60,6 +62,7 @@ enum {
     SIFIVE_U_PRCI,
     SIFIVE_U_UART0,
     SIFIVE_U_UART1,
+    SIFIVE_U_OTP,
     SIFIVE_U_DRAM,
     SIFIVE_U_GEM
 };