firmware: add extensible firmware params

As the firmware API evolves we keep extending functions with more arguments.
Stop this nonsense by proving an extensible data structure which can be used
to represent both user parameters and private internal parameters.

We introduce 3 data structures:

  o struct fw_req_params - used for user specified parameters
  o struct fw_priv_params - used for internal use only
  o struct fw_params - stiches both of the the above together,
				only for internal use

This starts off by just making the existing APIs use the new data
structures, it will make subsequent changes easier to review which will
be adding new flexible APIs.

A side consequences is get to replace all the old internal "firmware
behavior  options" flags with enums we properly document, remove the
blinding #ifdefs, and compartamentlize the userhelper fallback code
more appropriately unde CONFIG_FW_LOADER_USER_HELPER_FALLBACK.

This commit should introduces no functional changes (TM).

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>