sdhci: Add support for hosts reporting inverted write-protect state

This patch adds SDHCI_QUIRK_INVERTED_WRITE_PROTECT quirk. When
specified, the sdhci driver will invert WP state.

p.s. Actually, the quirk is more board-specific than
     controller-specific.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index fc7cb48..c814220 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1149,6 +1149,8 @@
 
 	spin_unlock_irqrestore(&host->lock, flags);
 
+	if (host->quirks & SDHCI_QUIRK_INVERTED_WRITE_PROTECT)
+		return !!(present & SDHCI_WRITE_PROTECT);
 	return !(present & SDHCI_WRITE_PROTECT);
 }