fs/zonefs: Use the enum req_op type for tracing request operations

Improve static type checking by using the enum req_op type for request
operations.
Reviewed-by: NJohannes Thumshirn <jth@kernel.org>
Reviewed-by: NDamien Le Moal <damien.lemoal@opensource.wdc.com>
Cc: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220714180729.1065367-64-bvanassche@acm.orgSigned-off-by: NJens Axboe <axboe@kernel.dk>

fs/zonefs/trace.h

@@ -25,7 +25,7 @@ TRACE_EVENT(zonefs_zone_mgmt,
 	    TP_STRUCT__entry(
 			     __field(dev_t, dev)
 			     __field(ino_t, ino)
-			     __field(int, op)
+			     __field(enum req_op, op)
 			     __field(sector_t, sector)
 			     __field(sector_t, nr_sectors)
 	    ),