fip_create: miscellaneous improvements to source code

fip_create: miscellaneous improvements to source code

This patch introduces the following improvements:

  * Global variables in fip_create.c declared static.
  * Flags to signal the requested actions (do_dump, do_pack) made
    global.
  * The ToC is printed at the end of the main funcion, after the FIP
    has been created/updated, not in the parse_cmdline() function.
  * Short format added to the command line options (-d,--dump;
    -h,--help).
  * Help message updated.

Change-Id: I5f08273c76f1de45fe597e290bee4b60aa404df9