ice: clean up __ice_aq_get_set_rss_lut()

Refactor __ice_aq_get_set_rss_lut() to improve reader experience and limit
misuse scenarios (undesired LUT size for given LUT type).

Allow only 3 RSS LUT type+size variants:
PF LUT sized 2048, GLOBAL LUT sized 512, and VSI LUT sized 64, which were
used on default flows prior to this commit.

Prior to the change, code was mixing the meaning of @params->lut_size and
@params->lut_type, flag assigning logic was cryptic, while long defines
made everything harder to follow.

Fix that by extracting some code out to separate helpers.
Drop some of "shift by 0" statements that originated from Intel's
internal HW documentation.

Drop some redundant VSI masks (since ice_is_vsi_valid() gives "valid" for
up to 0x300 VSIs).

After sweeping all the defines out of struct ice_aqc_get_set_rss_lut,
it fits into 7 lines.

Finally apply some cleanup to the callsite
(use of the new enums, tmp var for lengthy bit extraction).

Note that flags for 128 and 64 sized VSI LUT are the same,
and 64 is used everywhere in the code (updated to new enum here), it just
happened that there was 128 in flag name.

__ice_aq_get_set_rss_key() uses the same VSI valid bit, make constant
common for it and __ice_aq_get_set_rss_lut().

Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>