mmc: core: complete HS400 before checking status

We don't have a reproducible error case, yet our BSP team suggested that
the mmc_switch_status() command in mmc_select_hs400() should come after
the callback into the driver completing HS400 setup. It makes sense to
me because we want the status of a fully setup HS400, so it will
increase the reliability of the mmc_switch_status() command.

Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Fixes: ba6c7ac3 ("mmc: core: more fine-grained hooks for HS400 tuning")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>