[RFC] mkeficapsule: change the syntax

[AKASHI Takahiro]

At present, mkeficapsule supports only two type: FIT and raw.
User specifies the capsule type with --fit or --raw, respectively.
This syntax will be inconvenient in the future when another capsule
type is added. What mkeficapsule does is the exact same for whatever
capsule type the FW binary is.
So I'd like to introduce a new option, "--guid <guid>".
Accordingly, a small syntax change is preferable, that is:
Current form:
   $ mkeficapsule [--fit <fw bin> | --raw <fw bin>] <capsule file>
to:
   $ mkeficapsule [--fit | --raw | --guid <guid>] <fw bin> <capsule file>


-Takahiro Akashi