scsi: sd: Fix typo in sd_first_printk()

[likunyur]

added the macro sd_first_printk(). The macro takes "sdsk" as argument but dereferences "sdkp". This hasn't caused any real issues since all callers of sd_first_printk() have an sdkp. But fix the typo.

Signed-off-by: Li kunyu [email protected]