cmd: blk: remove unreachable code

Remove an unreachable return statement.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

cmd/blk_common.c

@@ -95,8 +95,6 @@ int blk_common_cmd(int argc, char * const argv[], enum if_type if_type,
 		} else {
 			return CMD_RET_USAGE;
 		}
-
-		return 0;
 	}
 }
 #endif