s390/eadm: fix CONFIG_BLOCK include dependency

Commit 2a842acab109 ("block: introduce new block status code type")
added blk_status_t usage to the eadm subchannel driver. However
blk_status_t is unknown when included via <linux/blkdev.h> for CONFIG_BLOCK=n.

Only include <linux/blk_types.h> since this is the only dependency eadm has.

This fixes build failures like below:
In file included from drivers/s390/cio/eadm_sch.c:24:0:
./arch/s390/include/asm/eadm.h:111:4: error: unknown type name 'blk_status_t'; did you mean 'si_status'?
blk_status_t error);

Reported-by: Heiko Carstens <[e-mail]>
Signed-off-by: Sebastian Ott <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/include/asm/eadm.h

···
 
 #include <linux/types.h>
 #include <linux/device.h>
-#include <linux/blkdev.h>
+#include <linux/blk_types.h>
 
 struct arqb {
 	u64 data;