UPSTREAM: mmc: host: sdhci-sprd: Add software queue support

Add software queue support to improve the performance.

bug: 151514181
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/f629b32943aae9e30ffa17acf4af06c270417001.1581478569.git.baolin.wang7@gmail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
(cherry picked from commit f4498549e1690af7cba1eff8570da9c134cb80b5)
Change-Id: Idbe8c95844196ff4791f9517d800f0b94117f48d