Ramdisk in the manifest, simplify initrd generation

We currently support loading a ramdisk for the primary. In fact, all
primaries are required to have one called 'initrd.img'. This makes
the ramdisk optional and specifies its filename in the manifest.

With that, generate_initrd.py loses the last remaining hardcoded
assumption about the structure of the Hafnium ramdisk. Refactor the
script and the build so that generate_initrd.py simply accepts a list of
(name in ramdisk, path on host) pairs.

Bug: 117551352
Change-Id: Iff2d70205940a1740c473d1cac34d5a05d6d6791
diff --git a/src/boot_flow/android.c b/src/boot_flow/android.c
index cf7246e..0221674 100644
--- a/src/boot_flow/android.c
+++ b/src/boot_flow/android.c
@@ -51,10 +51,12 @@
  * Android boot flow does not change based on the updates.
  */
 bool plat_boot_flow_update(struct mm_stage1_locked stage1_locked,
+			   const struct manifest *manifest,
 			   struct boot_params_update *p, struct memiter *cpio,
 			   struct mpool *ppool)
 {
 	(void)stage1_locked;
+	(void)manifest;
 	(void)p;
 	(void)cpio;
 	(void)ppool;