mmc: core: Allow hosts to specify non-support for SD commands

There are host drivers which needs to valdiate for non-supported SD
commands and returnn error code for such requests.

To improve and simplify the behaviour, let's invent MMC_CAP2_NO_SD
which these host drivers can set to tell the mmc core to skip sending SD
commands during card initialization.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index d72c0c3..c22476d 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -309,6 +309,7 @@
 #define MMC_CAP2_NO_WRITE_PROTECT (1 << 18)	/* No physical write protect pin, assume that card is always read-write */
 #define MMC_CAP2_NO_SDIO	(1 << 19)	/* Do not send SDIO commands during initialization */
 #define MMC_CAP2_HS400_ES	(1 << 20)	/* Host supports enhanced strobe */
+#define MMC_CAP2_NO_SD		(1 << 21)	/* Do not send SD commands during initialization */
 
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */