mmc: dw_mmc: Do not export dwmci_send_cmd() and dwmci_set_ios()

mmc: dw_mmc: Do not export dwmci_send_cmd() and dwmci_set_ios()

Do not over-expose the private dw_mmc API. The glue layer drivers at
this point shouldn't be aware and shouldn't use the generic
dwmci_send_cmd() and dwmci_set_ios() functions. Making those functions
public causes a "leaky abstraction" issue. It clutters the public
interface of generic dw_mmc driver and possibly leads to improper usage
of those functions, so it's a bad design.

If struct dm_dwmci_ops has to be extended, do so by copying it first
(like it's done for example in snps_dw_mmc driver). That also makes sure
the future changes to struct dm_dwmci_ops in dw_mmc driver will be
automatically reflected in all extended copies, and avoid code
duplication.

This effectively reverts commit ef3b16bb8e73 ("mmc: dw_mmc: export
dwmci_send_cmd() and dwmci_set_ios()").

No functional change.

Fixes: ef3b16bb8e73 ("mmc: dw_mmc: export dwmci_send_cmd() and dwmci_set_ios()")
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>