btrfs-progs: convert: update help format

Copy the style of util-linux utilities: single letter option + ", " + long
option name.

Signed-off-by: David Sterba <dsterba@suse.com>

Author: kdave

convert/main.c

@@ -1860,18 +1860,18 @@ static const char * const convert_usage[] = {
 	"In-place conversion from other filesystems to BTRFS",
 	"",
 	"Options:",
-	OPTLINE("-d|--no-datasum", "disable data checksum, sets NODATASUM"),
-	OPTLINE("-i|--no-xattr", "ignore xattrs and ACLs"),
-	OPTLINE("-n|--no-inline", "disable inlining of small files to metadata"),
+	OPTLINE("-d, --no-datasum", "disable data checksum, sets NODATASUM"),
+	OPTLINE("-i, --no-xattr", "ignore xattrs and ACLs"),
+	OPTLINE("-n, --no-inline", "disable inlining of small files to metadata"),
 	OPTLINE("--csum TYPE", ""),
 	OPTLINE("--checksum TYPE", "checksum algorithm to use (default: crc32c)"),
-	OPTLINE("-N|--nodesize SIZE", "set filesystem metadata nodesize"),
-	OPTLINE("-r|--rollback", "roll back to the original filesystem"),
-	OPTLINE("-l|--label LABEL", "set filesystem label"),
-	OPTLINE("-L|--copy-label", "use label from converted filesystem"),
+	OPTLINE("-N, --nodesize SIZE", "set filesystem metadata nodesize"),
+	OPTLINE("-r, --rollback", "roll back to the original filesystem"),
+	OPTLINE("-l, --label LABEL", "set filesystem label"),
+	OPTLINE("-L, --copy-label", "use label from converted filesystem"),
 	OPTLINE("--uuid SPEC", "new, copy or user-defined conforming UUID"),
-	OPTLINE("-p|--progress", "show converting progress (default)"),
-	OPTLINE("-O|--features LIST", "comma separated list of filesystem features"),
+	OPTLINE("-p, --progress", "show converting progress (default)"),
+	OPTLINE("-O, --features LIST", "comma separated list of filesystem features"),
 	OPTLINE("--no-progress", "show only overview, not the detailed progress"),
 	"",
 	"General:",