lightnvm: remove unnecessary field from nvm_rq

Remove the wait filed in nvm_rq. It is not used anymore, as targets rely
on the functionality provided by the LightNVM subsystem when sending
sync I/O.
Signed-off-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

include/linux/lightnvm.h

@@ -233,7 +233,6 @@ struct nvm_rq {
 	void *meta_list;
 	dma_addr_t dma_meta_list;
 
-	struct completion *wait;
 	nvm_end_io_fn *end_io;
 
 	uint8_t opcode;