Integrate with fastboot HAL to get partition type

Bug: 79480454
Bug: 78793464

Test: fastboot getvar partition-type:userdata

Change-Id: Ib096ee8061568b8503f3a3f2dbb7e19a932162c4
diff --git a/fastboot/constants.h b/fastboot/constants.h
index 063cd40..3bac0f9 100644
--- a/fastboot/constants.h
+++ b/fastboot/constants.h
@@ -53,6 +53,7 @@
 #define FB_VAR_HAS_SLOT "has-slot"
 #define FB_VAR_SLOT_COUNT "slot-count"
 #define FB_VAR_PARTITION_SIZE "partition-size"
+#define FB_VAR_PARTITION_TYPE "partition-type"
 #define FB_VAR_SLOT_SUCCESSFUL "slot-successful"
 #define FB_VAR_SLOT_UNBOOTABLE "slot-unbootable"
 #define FB_VAR_IS_LOGICAL "is-logical"