openrisc: Fix build errors

With kernel.org toolchain, it reports:

  CC      arch/openrisc/lib/board.o
  arch/openrisc/lib/board.c:56:2: error: 'console_init_f' undeclared here (not in a function)
  arch/openrisc/lib/board.c: In function 'board_init':
  arch/openrisc/lib/board.c:120:2: warning: implicit declaration of function 'console_init_r'
  make[1]: *** [arch/openrisc/lib/board.o] Error 1
  make: *** [arch/openrisc/lib] Error 2

Include console.h will fix this.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>