feat(handoff): add TE's for BL1 handoff interface

`TL_TAG_RW_MEM_LAYOUT64` encapsulates a structure used to represent the
layout of a region of memory on 64-bit platforms [2]. In TF-A this is
used to represent the `meminfo_t` structure passed between BL1 and BL2,
which provides BL2 with information about the space it has available in
BL2. The `TL_TAG_TB_FW_CONFIG` entry type encapsulates the trusted
bootloader firmware configuration [1].

[1] https://github.com/FirmwareHandoff/firmware_handoff/pull/37
[2] https://github.com/FirmwareHandoff/firmware_handoff/pull/36

Change-Id: I1e0eeec2ec204e469896490d42a9dce9b1b2f209
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>

include/lib/transfer_list.h

@@ -44,6 +44,8 @@ enum transfer_list_tag_id {
 	TL_TAG_OPTEE_PAGABLE_PART = 0x100,
 	TL_TAG_DT_SPMC_MANIFEST = 0x101,
 	TL_TAG_EXEC_EP_INFO64 = 0x102,
+	TL_TAG_TB_FW_CONFIG = 0x103,
+	TL_TAG_SRAM_LAYOUT64 = 0x104,
 };
 
 enum transfer_list_ops {