Replacing fs_mgr_read_fstab() with new fs_mgr APIs

The fstab settings of early-mounted partitions (e.g., /vendor)
will be in kernel device tree. Switch to the new API to get the
whole settings with those in device tree:

    fs_mgr_read_fstab_with_dt("/fstab.device")

The original default /fstab.{ro.hardware} might be moved to
/vendor/etc/. or /odm/etc/. Use another new API to get the default
fstab instead of using the hard-coded /fstab.{ro.hardware}.
This API also includes the settings from device tree:

    fs_mgr_read_fstab_default()

Bug: 35811655
Test: boot sailfish
Change-Id: If8361d891e17fa98b407b0e70f9f8984afcbcfe7
diff --git a/utils_android.cc b/utils_android.cc
index a4f1ea8..bda7337 100644
--- a/utils_android.cc
+++ b/utils_android.cc
@@ -28,16 +28,11 @@
 // Open the appropriate fstab file and fallback to /fstab.device if
 // that's what's being used.
 static struct fstab* OpenFSTab() {
-  char propbuf[PROPERTY_VALUE_MAX];
-  struct fstab* fstab;
-
-  property_get("ro.hardware", propbuf, "");
-  string fstab_name = string("/fstab.") + propbuf;
-  fstab = fs_mgr_read_fstab(fstab_name.c_str());
+  struct fstab* fstab = fs_mgr_read_fstab_default();
   if (fstab != nullptr)
     return fstab;
 
-  fstab = fs_mgr_read_fstab("/fstab.device");
+  fstab = fs_mgr_read_fstab_with_dt("/fstab.device");
   return fstab;
 }