mmc: sh_mmcif: report all errors

mmc: sh_mmcif: report all errors

Make error reporting in the driver more verbose. This patch is based on
an earlier work by Teppei Kamijou, but we try to not add any new error
messages to the log in the normal case to avoid confusing the user, and
also add a few more dev_dbg() calls.

Signed-off-by: Teppei Kamijou <[email protected]>
Signed-off-by: Shinya Kuribayashi <[email protected]>
[[email protected]: avoid producing new errors in normal case]
Signed-off-by: Guennadi Liakhovetski <[email protected]>
Signed-off-by: Chris Ball <[email protected]>