ARM: OMAP3xxx: HSMMC: avoid erratum workaround when transceiver is attached

If transceiver is attached to a MMC host of ES2.1 OMAP35xx, it seems
2.1.1.128 erratum doesn't apply and there is no data corruption,
probably because of different signal timing. The workaround for this
erratum disables multiblock reads, which causes dramatic loss of
performance (over 75% slower), so avoid it when transceiver is present.

Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
[paul@pwsan.com: edited commit message slightly]
Signed-off-by: Paul Walmsley <paul@pwsan.com>