mmc: support unsafe resume of cards

Since many have the system root on MMC/SD we must allow some foot
shooting when it comes to resume.

We cannot detect if a card is removed and reinserted during suspend,
so the safe approach would be to assume it was, avoiding potential
filesystem corruption. This will of course not work if you cannot
release the card before suspend.

This commit adds a compile time option that makes the MMC layer
assume the card wasn't touched if it is redetected upon resume.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index c7d64c0..6c97491 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -19,6 +19,8 @@
 	  This is an option for use by developers; most people should
 	  say N here.  This enables MMC core and driver debugging.
 
+source "drivers/mmc/core/Kconfig"
+
 source "drivers/mmc/card/Kconfig"
 
 source "drivers/mmc/host/Kconfig"