[coreboot] small bug/typo in filo payload (r80)

[Roman Yeryomin]

If not including GRUB interface functionality make falls out with error:

make
  CC      build/i386/context.o
  AS      build/i386/switch.S.o
  CC      build/i386/segment.o
  CC      build/i386/timer.o
  CC      build/i386/sys_info.o
  CC      build/i386/linux_load.o
  CC      build/main/filo.o
/home/wiz/dev/coreboot/filo-r80/main/filo.c: In function 'platform_reboot':
/home/wiz/dev/coreboot/filo-r80/main/filo.c:97: warning: implicit
declaration of function 'grub_printf'
  CC      build/main/elfload.o
  CC      build/main/elfnote.o
  CC      build/main/ipchecksum.o
  CC      build/main/strtox.o
  CC      build/fs/blockdev.o
  CC      build/fs/vfs.o
  CC      build/fs/fsys_ext2fs.o
  CC      build/drivers/ide.o
  CC      build/drivers/intel.o
  CC      build/drivers/flash/lxflash.o
/home/wiz/dev/coreboot/filo-r80/drivers/flash/lxflash.c: In function
'NAND_close':
/home/wiz/dev/coreboot/filo-r80/drivers/flash/lxflash.c:528: warning:
no return statement in function returning non-void
/home/wiz/dev/coreboot/filo-r80/drivers/flash/lxflash.c: In function
'NAND_readPage':
/home/wiz/dev/coreboot/filo-r80/drivers/flash/lxflash.c:652: warning:
unused variable 'bData'
/home/wiz/dev/coreboot/filo-r80/drivers/flash/lxflash.c: At top level:
/home/wiz/dev/coreboot/filo-r80/drivers/flash/lxflash.c:349: warning:
'NAND_writeData' defined but not used
  LD      build/filo
/home/wiz/dev/coreboot/filo-r80/build/main/filo.o: In function
`platform_reboot':
filo.c:(.text+0xa): undefined reference to `grub_printf'
make: *** [/home/wiz/dev/coreboot/filo-r80/build/filo] Error 1


can be fixed in filo.c like this:

#if CONFIG_USE_GRUB
void __attribute__((weak)) platform_reboot(void)
{
    grub_printf("Rebooting not supported.\n");
}
#endif


Roman