mmc_helper: add mmc_helper and rename mmc_fdt_helper to mmc_helper

[bag_semihalf.com]

Summary

Add generic mmc_helper which uses device_get_property api.

Rename mmc_fdt_helper structure to mmc_helper to get rid of redundant code.

[manu]

Code looks ok but that will break out of tree drivers (even if I'm sure that no such out of tree drivers using mmc_fdt_helpers exists) so I'm not too sure about this change.

[bag_semihalf.com]

I can add a macro like this somewhere in mmc_fdt_helper.h header, to keep it backwards compatible.

#define mmc_fdt_helper mmc_helper

[manu]

In D31598#712761, @bag_semihalf.com wrote:

I can add a macro like this somewhere in mmc_fdt_helper.h header, to keep it backwards compatible.

#define mmc_fdt_helper mmc_helper

Yes please.

[bag_semihalf.com]

I've added the macro. Should I revert the changes in other drivers? I didn't do it now, cause I think this could encourage people to use the new structure.

[manu]

In D31598#714885, @bag_semihalf.com wrote:

I've added the macro. Should I revert the changes in other drivers? I didn't do it now, cause I think this could encourage people to use the new structure.

No, all drivers should use the new struct.