mmc: forced sector mode when accessing OCR register

Some eMMC require this setting to work properly.
Tested on:
 - Toshiba THGBM2G8D8FBAIB (the one giving the problem)
 - Toshiba THGBM4G4D1HBAR
 - Micron MTFC4GMVEA
 - Hynix H26M64002BNR
 - SanDisk SDIN5E1-32G

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We changed e-MMC from SanDisk SDIN5D1-2G to Micron MTFC4GMVEA.
Received 'Card did not respond to voltage select' without the patch.

Line numbers had to be changed for the import.
-mkr-

Signed-off-by: Davide Bonfanti <davide.bonfanti@bticino.it>
Signed-off-by: Michael Krummsdorf <michael.krummsdorf@tqs.de>
Revert "Don't try sd card ops (avoids warnings)"

This reverts commit 679106160ff2fff25e08dbf181f44db7c36010e3.
We should keep close to upstream.

Signed-off-by: Michael Heimpold <mhe@iequalize.de>