mmc: replace BUG_ON with WARN_ON

Replace all cases of BUG_ON with WARN_ON where there is a chance
(with varying degrees of slim) that the kernel can continue without
incidence.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index ba7a847..6ba4589 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -264,7 +264,7 @@
 	unsigned int max_dtr;
 
 	BUG_ON(!host);
-	BUG_ON(!host->claimed);
+	WARN_ON(!host->claimed);
 
 	/*
 	 * Since we're changing the OCR value, we seem to
@@ -558,7 +558,7 @@
 	int err;
 
 	BUG_ON(!host);
-	BUG_ON(!host->claimed);
+	WARN_ON(!host->claimed);
 
 	mmc_attach_bus(host, &mmc_ops);