mmc: sdhci-msm: Add support for vendor capabilities registers

Some versions of this controller do not advertise their 3.0v and
8bit bus-width support capabilities. It is required to explicitly
set these capabilities for the specific controller versions.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>