Implement CMD53 block mode support for SDHCI and AllWinner-based boards

[kibab]

Summary

If a custom block size requested, use it, otherwise revert to the previous logic
of using just a data size if it's less than MMC_BLOCK_SIZE, and MMC_BLOCK_SIZE otherwise.

Test Plan

Booted on Rpi3 and AllWinner NanoPi M1+, verified that mmc_da driver didn't break and
it's still possible to work with SD/MMC cards.
No code using the block mode exists in the tree now.

[bz]

The descriptions needs slightly rewording "is requested". I'd be a bit more verbose maybe explaining distinct use of block_size and block_count?

sys/dev/sdhci/sdhci.c

2814 ↗

(On Diff #55697)

I'd put <blank>: 0 for the last three lines like for len : 0, but that's only a style nit.

[kibab]

• Implement CMD53 block mode support for SDHCI and AllWinner-based boards
• Use the new MMC_DATA_BLOCK_SIZE
• Put blank before colon when printing command args

[kibab]

Updated to use MMC_DATA_BLOCK_SIZE.

sys/dev/sdhci/sdhci.c

2814 ↗

(On Diff #55697)

Ack

[imp]

OK. this looks good, and you are using the flag I was complaining about not being used , so ignore that bit.
This is conditional on D19779.
and I'm ENOCLUE on the hardware, but it looks like it might be right.