mmc: sdhci: Report failure reasons for all cases in sdhci_add_host()

For most error conditions sdhci_add_host() will print a diagnostic
message indicating why it failed but there are a few cases where this
does not happen. Add error messages in these cases to aid diagnosis.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Chris Ball <cjb@laptop.org>