misc: replace manual From<T> for *Error with #[from]

This is a small simplification we can use since we use `thiserror`
anyway. Note that `#[from]` implies `#[source]` [0].

[0]: https://docs.rs/thiserror/2.0.12/thiserror/index.html

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

arch/src/riscv64/mod.rs

@@ -46,12 +46,6 @@ pub enum Error {
     RegsConfiguration(#[source] hypervisor::HypervisorCpuError),
 }
 
-impl From<Error> for super::Error {
-    fn from(e: Error) -> super::Error {
-        super::Error::PlatformSpecific(e)
-    }
-}
-
 #[derive(Debug, Copy, Clone)]
 /// Specifies the entry point address where the guest must start
 /// executing code.