rust: hpet: rename hpet module to "device"

Follow a similar convention as pl011.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/hw/timer/hpet/src/lib.rs

@@ -7,7 +7,7 @@
 //! This library implements a device model for the IA-PC HPET (High
 //! Precision Event Timers) device in QEMU.
 
+pub mod device;
 pub mod fw_cfg;
-pub mod hpet;
 
 pub const TYPE_HPET: &::std::ffi::CStr = c"hpet";