Fix the warning/error:
drivers/mci/mci-core.c: In function 'mci_card_probe':
drivers/mci/mci-core.c:1195: warning: implicit declaration of function 'pr_warn'
...
drivers/built-in.o: In function `mci_card_probe':
mc13892.c:(.text.mci_card_probe+0x68): undefined reference to `pr_warn'
Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>