mmc: sdhci-msm: set sdma_boundary to zero

Programming legacy HOST SDMA Buffer Boundary bits in Block Size Register
(0x04) is not supported in Qualcomm sdhci controllers. Writing to this
would cause the controller not to transfer last block in case block size
is 4 bytes or less.

This issue was noticed while testing sdio wlan card on Qcom DB410c board.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>