lightnvm: complete geo structure with maxoc*

Complete the generic geometry structure with the maxoc and maxocpu
felds, present in the 2.0 spec. Also, expose them through sysfs.

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

include/linux/lightnvm.h

@@ -296,6 +296,8 @@ struct nvm_geo {
 	u32	ws_min;		/* minimum write size */
 	u32	ws_opt;		/* optimal write size */
 	u32	mw_cunits;	/* distance required for successful read */
+	u32	maxoc;		/* maximum open chunks */
+	u32	maxocpu;	/* maximum open chunks per parallel unit */
 
 	/* device capabilities */
 	u32	mccap;