If configured or default bus-width is wrong for the current hardware,
registration of card/emmc is likely to fail.  This patch adds more verbosity
in the case of a failed detection:

    | omap-hsmmc 48060000.mmc: registered as 48060000.mmc
    | mmc0: detected MMC card version 4.41
    | mmc0: Changing MMC bus width failed: -110
    | mmc0: Card's startup fails with -110

Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>