ARM SAMD M0 & SdFat require reduced clock

[constant-flow]

Error

When using the sdfat sample the code reports failure until you decrease the clock speed of the SD card.
This is an issue discussed here as well.

Testing

My board: Arduino MKR Wifi 1010
Example: Uno_and_above_SdFat

Fix

changing l.435 in Uno_and_above_SdFat.ino
from
if (!SD.begin(SD_CS_PIN)) {
to
if (!SD.begin(SD_CS_PIN, SD_SCK_MHZ(12))) {
fixed it for me.

Further details

The SdFat-QuickStart even uses only 4 MHz .

[siara-cc]

Hi sorry I saw this only now. It seems I haven't been getting notifications as I was not a Watcher for this repo.
Please see this comment: siara-cc/esp_arduino_sqlite3_lib#23 (comment)
It could be the reason for this issue.
Since there could be a lot of IO issues like this, I kept IO functions outside this library so the users can handle it if it does not work for them.