ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC

This approximately triples write performance for the SD card.  My card
is too full of important data to collect very reliable numbers, but I
see 271.361% +/- 166.742% improvement (n=3 before, 6 after), for 'dd
if=/dev/zero of=/boot/asdf bs=1M count=3 oflag=dsync,direct'.  Read
performance appears to be unaffected.
Signed-off-by: NEric Anholt <eric@anholt.net>
Acked-by: NStephen Warren <swarren@wwwdotorg.org>

arch/arm/configs/multi_v7_defconfig

@@ -642,7 +642,6 @@ CONFIG_MMC_SDHCI_SPEAR=y
 CONFIG_MMC_SDHCI_S3C=y
 CONFIG_MMC_SDHCI_S3C_DMA=y
 CONFIG_MMC_SDHCI_BCM_KONA=y
-CONFIG_MMC_SDHCI_BCM2835=y
 CONFIG_MMC_SDHCI_ST=y
 CONFIG_MMC_OMAP=y
 CONFIG_MMC_OMAP_HS=y