Bug fixes and initial card interrupt support in sdhc
Bug fixes and initial card interrupt support in sdhc

- Fix data transfers where c_datalen is not a multiple of 4
- Fix the handling of MMC commands with c_datalen < c_blklen
- Change the order of register writes in sdhc_start_command()
  and only write block count if we transfer multiple blocks
- Enable the SDIO card interrupt (but don't acknowledge it yet)

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars