efi_loader: out of memory in efi_add_memory_map_pg

Handle out of memory situation in efi_add_memory_map_pg().

Fixes: 5d00995c361c ("efi_loader: Implement memory allocation and map")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index e2ca78d..2c5d522 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -282,6 +282,8 @@
 
 	++efi_memory_map_key;
 	newlist = calloc(1, sizeof(*newlist));
+	if (!newlist)
+		return EFI_OUT_OF_RESOURCES;
 	newlist->desc.type = memory_type;
 	newlist->desc.physical_start = start;
 	newlist->desc.virtual_start = start;