refactor(userspace): split syscall/fat16/ext4 by concern; trim comments

crates/libkos/src/device.rs

@@ -1,8 +1,5 @@
-//! Handing devices to drivers. Init holds every device's capabilities
-//! (see `types::bootinfo`) and gives each driver its own over the driver's
-//! endpoint, one capability per `Call`; the driver collects them before it
-//! starts serving. Drivers then map their MMIO and allocate DMA memory
-//! themselves; nothing is set up for them behind their back.
+//! Init hands each driver its device's capabilities, one per `Call` on the
+//! driver's endpoint; drivers map MMIO and allocate DMA themselves.
 
 use crate::syscall::{self, Received, Result};
 use types::address::VirtualAddress;