serial: mxc: Support bulk enabling clocks

serial: mxc: Support bulk enabling clocks

Depending on the platform, there may be multiple clock sources
required to enable a UART.  Use the bulk functions to get and
enable the clocks when the UART probes.  This can facilitate
the removal of functions to manually enable the clock.

This is made dependent on CLK_CCF which is used on imx6q,
imx8m[mnqp], several imxrt, imx9.  If/when the UART clock
registration is done for older boards, this limitation
could be updated.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>