MLK-10629-4 mmc: sdhci: remove MMC_CAP_NEEDS_POLL

This will cause meaningless CPU overhead by polling the card at backgroud
if the CD is broken.
Most board does not intend to use this function, so remove it.
Platform driver could add it for test if needed.

Signed-off-by: Dong Aisheng <b29396@freescale.com>

Conflicts:
	drivers/mmc/host/sdhci.c