Relax Update requirements by dropping ESRT

The ESRT support in U-Boot is immature and not ready for mainline.
Temporarily remove the ESRT requirement so that platforms can meaningfully
conform to EBBR. When ESRT functionality has matured this requirement will
can be brought back in.

Signed-off-by: Grant Likely <[email protected]>

source/chapter2-uefi.rst

@@ -467,17 +467,14 @@ EBBR platforms are required to implement either an in-band or an out-of-band fir
 If firmware update is performed in-band (firmware on the application processor updates itself),
 then the firmware shall implement the `UpdateCapsule()` runtime service and accept updates in the
 "Firmware Management Protocol Data Capsule Structure" format as described in [UEFI]_ § 23.3,
-"Delivering Capsules Containing Updates to Firmware Management Protocol.  [#FMPNote]_
-Firmware is also required to provide an EFI System Resource Table (ESRT). [UEFI]_ § 23.4
-Every firmware image that can be updated in-band must be described in the ESRT.
+"Delivering Capsules Containing Updates to Firmware Management Protocol."
 
 If firmware update is performed out-of-band (e.g., by an independent Baseboard
 Management Controller (BMC), or firmware is provided by a hypervisor),
 then the platform is not required to implement the `UpdateCapsule()` runtime service.
 
 `UpdateCapsule()` is only required before `ExitBootServices()` is called.
 
-
 .. [#OPTEESupplicant] It is worth noting that OP-TEE has a similar problem
    regarding secure storage.
    OP-TEE's chosen solution is to rely on an OS supplicant agent to perform
@@ -488,11 +485,3 @@ then the platform is not required to implement the `UpdateCapsule()` runtime ser
    during runtime services.
 
    https://optee.readthedocs.io/en/latest/architecture/secure_storage.html
-
-.. [#FMPNote] The `UpdateCapsule()` runtime service is expected to be suitable
-   for use by generic firmware update services like fwupd and Windows Update.
-   Both fwupd and Windows Update read the ESRT table to determine what firmware
-   can be updated, and use an EFI helper application to call `UpdateCapsule()`
-   before `ExitBootServices()` is called.
-
-   https://fwupd.org/