mmc: sdhci-bcm2835: remove driver

The sdhci-bcm2835 is no more needed since it has been replaced
by sdhci-iproc.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>