mmc: increase SD write timeout for crappy cards

It seems that some cards are slightly out of spec and occasionally
will not be able to complete a write in the alloted 250 ms [1].
Incease the timeout slightly to allow even these cards to function
properly.

[1] http://lkml.org/lkml/2008/9/23/390Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/core/core.c

@@ -280,7 +280,11 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
 			(card->host->ios.clock / 1000);
 
 		if (data->flags & MMC_DATA_WRITE)
-			limit_us = 250000;
+			/*
+			 * The limit is really 250 ms, but that is
+			 * insufficient for some crappy cards.
+			 */
+			limit_us = 300000;
 		else
 			limit_us = 100000;