nvme: initialize get-feature command result value as zero

This is to resolve the build error below.

../nvme.c:4851:9: error: ‘result’ may be used uninitialized [-Werror=maybe-uninitialized]
 4851 |         nvme_show_feature(cfg.feature_id, cfg.sel, result, buf, ...
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 4852 |                           flags);
      |                           ~~~~~~
../nvme.c: In function ‘get_feature’:
../nvme.c:4874:15: note: ‘result’ was declared here
 4874 |         __u64 result;
      |               ^~~~~~

Signed-off-by: Tokunori Ikegami <[email protected]>

Author: ikegami-t

nvme.c

@@ -4871,7 +4871,7 @@ static int get_feature_id_changed(struct libnvme_transport_handle *hdl, struct f
 	__cleanup_free void *buf_def = NULL;
 	__cleanup_free void *buf = NULL;
 	__u64 result_def = 0;
-	__u64 result;
+	__u64 result = 0;
 	int err_def = 0;
 	int err;