Use information about max data size that the controller is able to operate

[kibab]

Summary

Using DFLTPHYS/MAXPHYS is not always OK, instead make it possible for the
controller driver to provide maximum data size to MMCCAM, and use it there.

The old stack already does this.

[manu]

The Allwinner part seems ok.

[imp]

sys/cam/mmc/mmc_da.c

1503

min(<this stuff>, MAXPHYS);

sys/dev/sdhci/sdhci.c

2606

where does the mmc.host_maxa_data get set here? It looks like the break should be deleted and then 'else max_data = 65536;' added.

[kibab]

• Address comments in D15892 wrt max_data setting and MIN(MAX_PHYS,...)
• MIN(MAXPHYS) for D15892