tci: Fix compile failure by including qemu-common.h

Compilation of TCI was accidentally broken by the recent disassembler
changes:

  CC    x86_64-softmmu/arch_init.o
In file included from target-i386/cpu-qom.h:23:0,
                 from target-i386/cpu.h:986,
                 from include/qemu-common.h:122,
                 from include/disas/bfd.h:12,
                 from disas/tci.c:20:
include/qom/cpu.h:178:43: error: unknown type name ‘disassemble_info’
     void (*disas_set_info)(CPUState *cpu, disassemble_info *info);
                                           ^
include/qom/cpu.h:179:1: error:
no semicolon at end of struct or union [-Werror]
 } CPUClass;
 ^
cc1: all warnings being treated as errors

The underlying cause of this is an include loop:
 bfd.h -> qemu-common.h -> target-arm/cpu.h ->  target-arm/cpu-qom.h
  -> qom/cpu.h -> bfd.h

which means that if bfd.h is included first then qom/cpu.h doesn't
get the definition of the disassemble_info type that it wanted.
The easiest fix for this is to include qemu-common.h from tci.c
before including disas/bfd.h.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
