efi: Increase default memory allocation to 32 MiB

We have multiple reports of things being slower with a 1 MiB initial static
allocation, and a report (more difficult to nail down) of a boot failure
as a result of the smaller initial allocation.

Make the initial memory allocation 32 MiB.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/efi/mm.c

@@ -39,7 +39,7 @@
 #define MEMORY_MAP_SIZE	0x3000
 
 /* The default heap size for GRUB itself in bytes.  */
-#define DEFAULT_HEAP_SIZE	0x100000
+#define DEFAULT_HEAP_SIZE	0x2000000
 
 static void *finish_mmap_buf = 0;
 static grub_efi_uintn_t finish_mmap_size = 0;