siena: Make SRIOV support specific for Siena

Add a Siena Kconfig option and use it in stead of the sfc one.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Inline functions in sriov.h to avoid conflicts with sfc

The implementation of each is quite short. This means sriov.c is
not needed any more.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc: Copy shared files needed for Siena (part 2)

These are the files starting with m through w.
No changes are done, those will be done with subsequent commits.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>