configs/rockpro64: Use mainline ATF

Use the mainline ATF as it supports the Pine64 ROCKPro64 board.

Fixes:
- https://gitlab.com/buildroot.org/buildroot/-/jobs/2812054016

Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit 0d198311b9d267b3883e9e979fc273f5c61e323c)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/rockpro64_defconfig

@@ -7,9 +7,8 @@ BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_8=y
 
 # Firmware
 BR2_TARGET_ARM_TRUSTED_FIRMWARE=y
-BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_GIT=y
-BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_REPO_URL="https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git"
-BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_REPO_VERSION="11a0a46a899fcc3b1fdb214b382f3d7495d88eca"
+BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION=y
+BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION_VALUE="v2.7"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_PLATFORM="rk3399"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_BL31=y
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_NEEDS_ARM32_TOOLCHAIN=y