efi: Add ESRT to the EFI system table

The ESRT is initialised during efi_init_objlist after
efi_initialize_system_table().

The ESRT is recreated from scratch at the following events:
- successful UpdateCapsule;
- FMP instance install.

The code ensures that every ESRT entry has a unique fw_class value.

Limitations:
- The ESRT is not updated if an FMP instance is uninstalled;
- the fields image_type and flags are in the current implementation left
undefined. Setting these values will require a per-platform function
that returns the image_type/flags as a function of the image fw_class.

CC: Heinrich Schuchardt	<xypron.glpk@gmx.de>
CC: Sughosh Ganu <sughosh.ganu@linaro.org>
CC: AKASHI Takahiro <takahiro.akashi@linaro.org>
CC: Ilias Apalodimas <ilias.apalodimas@linaro.org>
CC: Andre Przywara <andre.przywara@arm.com>
CC: Alexander Graf <agraf@csgraf.de>
CC: nd@arm.com
Signed-off-by: Jose Marinho <jose.marinho@arm.com>

Remove two EFI_CALL() indirections.
Move ESRT GUID in efidebug's list of GUIDs.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 0a41244..e44f004 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -342,4 +342,11 @@
 	  it is signed with a trusted key. To do that, you need to install,
 	  at least, PK, KEK and db.
 
+config EFI_ESRT
+	bool "Enable the UEFI ESRT generation"
+	depends on EFI_CAPSULE_FIRMWARE_MANAGEMENT
+	default y
+	help
+	  Enabling this option creates the ESRT UEFI system table.
+
 endif