target/riscv: Remove unused include of riscv_htif.h for virt board riscv

Signed-off-by: Jonathan Behrens <fintelia@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

hw/riscv/virt.c

@@ -29,7 +29,6 @@
 #include "hw/sysbus.h"
 #include "hw/char/serial.h"
 #include "target/riscv/cpu.h"
-#include "hw/riscv/riscv_htif.h"
 #include "hw/riscv/riscv_hart.h"
 #include "hw/riscv/sifive_plic.h"
 #include "hw/riscv/sifive_clint.h"