mmc: core: Refactor bus speed selection code

The bus speed selection code in mmc_card_init() is convoluted, refactor
the code to simplify this and make it simpler for adding new bus speed
capabilities.

Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index dbafdfc..5796b9d 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -245,6 +245,7 @@
 						/* DDR mode at 1.8V */
 #define MMC_CAP_1_2V_DDR	(1 << 12)	/* can support */
 						/* DDR mode at 1.2V */
+#define MMC_CAP_HSDDR		(MMC_CAP_1_8V_DDR | MMC_CAP_1_2V_DDR)
 #define MMC_CAP_POWER_OFF_CARD	(1 << 13)	/* Can power off after boot */
 #define MMC_CAP_BUS_WIDTH_TEST	(1 << 14)	/* CMD14/CMD19 bus width ok */
 #define MMC_CAP_UHS_SDR12	(1 << 15)	/* Host supports UHS SDR12 mode */