lightnvm: combine 1.2 and 2.0 command flags

Add nvm_set_flags helper to enable core to appropriately
set the command flags for read/write/erase depending on which version
a drive supports.

The flags arguments can be distilled into the access hint,
scrambling, and program/erase suspend. Replace the access hint with
a "is_seq" parameter. The rest of the flags are dependent on the
command opcode, which is trivial to detect and set.

Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/lightnvm.h

@@ -305,6 +305,8 @@ struct nvm_rq {
 	u64 ppa_status; /* ppa media status */
 	int error;
 
+	int is_seq; /* Sequential hint flag. 1.2 only */
+
 	void *private;
 };