efi_loader: bump EFI_SPECIFICATION_VERSION to 2.9

We have implemented all what is new in UEFI specification 2.9 and relevant
for U-Boot.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/include/efi_api.h b/include/efi_api.h
index 1e95656..80109f0 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -20,8 +20,8 @@
 #include <charset.h>
 #include <pe.h>
 
-/* UEFI spec version 2.8 */
-#define EFI_SPECIFICATION_VERSION (2 << 16 | 80)
+/* UEFI spec version 2.9 */
+#define EFI_SPECIFICATION_VERSION (2 << 16 | 90)
 
 /* Types and defines for EFI CreateEvent */
 enum efi_timer_delay {