[vmbase] Move RangeExt to vmbase for reuse

in both pvmfw and rialto.

No behavior change in this cl.

Bug: 284462758
Test: m pvmfw_img
Change-Id: Ifda7f4a2a08ebb6646c3c7e189a77c5ff3fe74a3
diff --git a/pvmfw/src/entry.rs b/pvmfw/src/entry.rs
index a2bd156..19ba9c3 100644
--- a/pvmfw/src/entry.rs
+++ b/pvmfw/src/entry.rs
@@ -18,7 +18,6 @@
 use crate::crypto;
 use crate::fdt;
 use crate::heap;
-use crate::helpers::RangeExt as _;
 use crate::memory::{self, MemoryTracker, MEMORY};
 use crate::rand;
 use core::arch::asm;
@@ -32,6 +31,7 @@
 use log::info;
 use log::warn;
 use log::LevelFilter;
+use vmbase::util::RangeExt as _;
 use vmbase::{
     console, layout, logger, main,
     memory::{min_dcache_line_size, SIZE_2MB, SIZE_4KB},