md: disable bcache

It uses anon semaphores
|drivers/md/bcache/request.c: In function ‘cached_dev_write_complete’:
|drivers/md/bcache/request.c:1007:2: error: implicit declaration of function ‘up_read_non_owner’ [-Werror=implicit-function-declaration]
|  up_read_non_owner(&dc->writeback_lock);
|  ^
|drivers/md/bcache/request.c: In function ‘request_write’:
|drivers/md/bcache/request.c:1033:2: error: implicit declaration of function ‘down_read_non_owner’ [-Werror=implicit-function-declaration]
|  down_read_non_owner(&dc->writeback_lock);
|  ^

either we get rid of those or we have to introduce them…

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>

Author: Sebastian Andrzej Siewior

drivers/md/bcache/Kconfig

@@ -1,6 +1,7 @@
 
 config BCACHE
 	tristate "Block device as cache"
+	depends on !PREEMPT_RT_FULL
 	---help---
 	Allows a block device to be used as cache for other devices; uses
 	a btree for indexing and the layout is optimized for SSDs.