intel/fs: New shuffle_for_32bit_write and shuffle_from_32bit_read

intel/fs: New shuffle_for_32bit_write and shuffle_from_32bit_read

These new shuffle functions deal with the shuffle/unshuffle operations
needed for read/write operations using 32-bit components when the
read/written components have a different bit-size (8, 16, 64-bits).
Shuffle from 32-bit to 32-bit becomes a simple MOV.

shuffle_src_to_dst takes care of doing a shuffle when source type is
smaller than destination type and an unshuffle when source type is
bigger than destination. So this new read/write functions just need
to call shuffle_src_to_dst assuming that writes use a 32-bit
destination and reads use a 32-bit source.

As shuffle_for_32bit_write/from_32bit_read components take components
in unit of source/destination types and shuffle_src_to_dst takes units
of the smallest type component, we adjust components and first_component
parameters.

To enable this new functions it is needed than there is no
source/destination overlap in the case of shuffle_from_32bit_read.
That never happens on shuffle_for_32bit_write as it allocates a new
destination register as it was at shuffle_64bit_data_for_32bit_write.

v2: Reword commit log and add comments to explain why first_component
    and components parameters are adjusted. (Jason Ekstrand)

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>