mmc: core: prepend 0x to OCR entry in sysfs

commit c892b0d81705c566f575e489efc3c50762db1bde upstream.

The sysfs entry "ocr" was missing the 0x prefix to identify it as hex
formatted.

Fixes: 5fb06af7 ("mmc: core: Extend sysfs with OCR register")
Signed-off-by: Bastian Stender <bst@pengutronix.de>
[Ulf: Amended change to also cover SD-cards]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>