sdhci: remove DMA capability check from controller's PCI Class reg

Many host controllers don't fully follow the PCI spec to claim
whether they support DMA in PCI class register. Leave the driver
to judge it from the Capability register, quirks and module parameter

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>