sdmmc: improve error handling during SPI mode init

sdmmc: improve error handling during SPI mode init

- In SPI mode, the card will respond to the initial SDIO reset (done
using CMD52) with “invalid command” error. Handle this correctly.

- sdmmc_card_init had a hack where GO_IDLE_STATE (CMD0) command was
sent twice. Add explanation why this is done, and don’t expect
correct response from the card on first CMD0.

- improve logs printed at debug level by adding CMD index