clk: fsl-sai: Add i.MX8M support with 8 byte register offset

clk: fsl-sai: Add i.MX8M support with 8 byte register offset

The i.MX8M/Mini/Nano/Plus variant of the SAI IP has control registers
shifted by +8 bytes and requires additional bus clock. Add support for
the i.MX8M variant of the IP with this register shift and additional
clock.

Reviewed-by: Brian Masney <bmasney@redhat.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Marek Vasut <marex@nabladev.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>