rebootescrow: use property to find device

To allow vendors to have different names for their devices, read the
device name from a system property.

Test: atest VtsHalRebootEscrowTargetTest
Bug: 146400078
Change-Id: I93f37e14139532ab192795dcad27c586545a1bc4
diff --git a/rebootescrow/aidl/default/RebootEscrow.cpp b/rebootescrow/aidl/default/RebootEscrow.cpp
index 94d0901..5ae96f6 100644
--- a/rebootescrow/aidl/default/RebootEscrow.cpp
+++ b/rebootescrow/aidl/default/RebootEscrow.cpp
@@ -29,7 +29,7 @@
 using ::android::base::unique_fd;
 
 ndk::ScopedAStatus RebootEscrow::storeKey(const std::vector<int8_t>& kek) {
-    int rawFd = TEMP_FAILURE_RETRY(::open(REBOOT_ESCROW_DEVICE, O_WRONLY | O_NOFOLLOW | O_CLOEXEC));
+    int rawFd = TEMP_FAILURE_RETRY(::open(devicePath_.c_str(), O_WRONLY | O_NOFOLLOW | O_CLOEXEC));
     unique_fd fd(rawFd);
     if (fd.get() < 0) {
         LOG(WARNING) << "Could not open reboot escrow device";
@@ -48,7 +48,7 @@
 }
 
 ndk::ScopedAStatus RebootEscrow::retrieveKey(std::vector<int8_t>* _aidl_return) {
-    int rawFd = TEMP_FAILURE_RETRY(::open(REBOOT_ESCROW_DEVICE, O_RDONLY | O_NOFOLLOW | O_CLOEXEC));
+    int rawFd = TEMP_FAILURE_RETRY(::open(devicePath_.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC));
     unique_fd fd(rawFd);
     if (fd.get() < 0) {
         LOG(WARNING) << "Could not open reboot escrow device";