mmc: sdhci-of-arasan: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix multiple
warnings by explicitly adding multiple break statements instead of
letting the code fall through to the next case.

Link: https://github.com/KSPP/linux/issues/115


Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/387cab3a466038aa5d1fc34b8b6a7c4f693826ea.1605896060.git.gustavoars@kernel.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>