keystore2: rename MonotonicRawTime to BootTime

Due to https://r.android.com/2822970 ("Use CLOCK_BOOTTIME for keystore2
auth token received time"), MonotonicRawTime now uses CLOCK_BOOTTIME
instead of CLOCK_MONOTONIC_RAW.  Therefore, rename it to BootTime.

Bug: 309686873
Test: atest -p --include-subdirs system/security/keystore2
Change-Id: If1fbbac2eccb03dc7360ae742d79e58f871fb80d
diff --git a/keystore2/src/database/perboot.rs b/keystore2/src/database/perboot.rs
index 7ff35fa..1b7c80d 100644
--- a/keystore2/src/database/perboot.rs
+++ b/keystore2/src/database/perboot.rs
@@ -15,7 +15,7 @@
 //! This module implements a per-boot, shared, in-memory storage of auth tokens
 //! and last-time-on-body for the main Keystore 2.0 database module.
 
-use super::{AuthTokenEntry, MonotonicRawTime};
+use super::{AuthTokenEntry, BootTime};
 use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{
     HardwareAuthToken::HardwareAuthToken, HardwareAuthenticatorType::HardwareAuthenticatorType,
 };
@@ -103,11 +103,11 @@
         matches.last().map(|x| x.0.clone())
     }
     /// Get the last time the device was off the user's body
-    pub fn get_last_off_body(&self) -> MonotonicRawTime {
-        MonotonicRawTime(self.last_off_body.load(Ordering::Relaxed))
+    pub fn get_last_off_body(&self) -> BootTime {
+        BootTime(self.last_off_body.load(Ordering::Relaxed))
     }
     /// Set the last time the device was off the user's body
-    pub fn set_last_off_body(&self, last_off_body: MonotonicRawTime) {
+    pub fn set_last_off_body(&self, last_off_body: BootTime) {
         self.last_off_body.store(last_off_body.0, Ordering::Relaxed)
     }
     /// Return how many auth tokens are currently tracked.