iwlwifi: expose static methods for MVM use

To support hybrid state of MVM op_mode, most of the functioanallity
will be done using DVM functions.

When MVM will have independant live, the declarations will be removed
and the functions will be static back.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>