ANDROID: GKI: Export memblock_free to drivers

On architectures that support the preservation of memblock metadata
after __init, allow drivers to call memblock_free() to free a
reservation made by early arch code. This is a hack to support the
freeing of bootsplash reservations passed to Linux by the bootloader.

(This should be reworked in future versions of Android; do not
cherry-pick this patch forward.)

Bug: 139653858
Bug: 174620135
Bug: 249340121
Change-Id: I32c0ee70c33c94deff70aa548896caa9978396fb
Signed-off-by: Alistair Delva <adelva@google.com>
(cherry picked from commit 2eeee9f41c)

android/abi_gki_aarch64.stg

@@ -338834,6 +338834,15 @@ elf_symbol {
   type_id: 0x01a85b76
   full_name: "memblock_end_of_DRAM"
 }
+elf_symbol {
+  id: 0x4fb91c54
+  name: "memblock_free"
+  is_defined: true
+  symbol_type: FUNCTION
+  crc: 0xa6ecab47
+  type_id: 0x1567dd7e
+  full_name: "memblock_free"
+}
 elf_symbol {
   id: 0xaa97e158
   name: "memchr"
@@ -369543,6 +369552,10 @@ symbols {
     key: "memblock_end_of_DRAM"
     value: 0x746374fa
   }
+  symbol {
+    key: "memblock_free"
+    value: 0x4fb91c54
+  }
   symbol {
     key: "memchr"
     value: 0xaa97e158

mm/memblock.c

@@ -849,6 +849,9 @@ int __init_memblock memblock_phys_free(phys_addr_t base, phys_addr_t size)
 	kmemleak_free_part_phys(base, size);
 	return memblock_remove_range(&memblock.reserved, base, size);
 }
+#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
+EXPORT_SYMBOL_GPL(memblock_free);
+#endif
 
 int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
 {