wflinfo: Don't modify struct options after initialization

parse_args() initializes global options. After that, options should be
immutable. To ensure that, constify each occurence of struct options as
a function parameter.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
wflinfo: Cleanup signature of wflinfo_try_create_context()

The function creates and returns two objects: a context and a config.
The context is the function's return value, and the config is an out
parameter.

Functions with asymmetric returns, I find awkard. Fix the signature to
return both objects as out parameters.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
wflinfo: Cleanup signature of wflinfo_create_context()

The function creates and returns two objects: a context and a config.
The context is the function's return value, and the config is an out
parameter.

Functions with asymmetric returns, I find awkard. Fix the signature to
return both objects as out parameters.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
wflinfo: Replace s/-1/WAFFLE_DONT_CARE/ when relevant

This clarifies the code's intent.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
wflinfo: Distinguish between cmdline options and func options

'struct options` is intended for cmdline options. But wflinfo repurposed
it to manage waffle_config attributes too by passing it into
wflinfo_create_context() and wflinfo_try_create_context().

Add a new type `struct wflinfo_config_attrs`.  Stop passing `struct
option` to those functions and pass wflinfo_config_attrs instead.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>