block: don't include <linux/idr.h> in blk.h

Not needed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-8-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk.h

@@ -2,7 +2,6 @@
 #ifndef BLK_INTERNAL_H
 #define BLK_INTERNAL_H
 
-#include <linux/idr.h>
 #include <linux/part_stat.h>
 #include <linux/blk-crypto.h>
 #include <linux/memblock.h>	/* for max_pfn/max_low_pfn */