arm-trusted-firmware-mediatek: fix boot hang on unifi-6-lr

The Ubiquiti Networks UniFi 6 LR access point comes with a total of
512 MB RAM provided by 2x 8-bit DDR3 SDRAM. This combination lead to
problems with the DDR calibration on boot resulting in occasional hang
on boot. Use updated calibration binary provided by MediaTek to make
boot on that device more reliable.
The binary has also been tested on the BananaPi BPi-R64 board and that
also works just fine with the new binary.

Signed-off-by: Daniel Golle <[email protected]>

package/boot/arm-trusted-firmware-mediatek/Makefile

@@ -13,9 +13,9 @@ PKG_RELEASE:=$(AUTORELEASE)
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=https://github.com/mtk-openwrt/arm-trusted-firmware.git
-PKG_SOURCE_DATE:=2021-03-10
-PKG_SOURCE_VERSION:=8b635f61091f2e5bce88269468c53fc30bb4cd64
-PKG_MIRROR_HASH:=ffe233a19b51504f605a90a88c7a1bb74303e4a7173a59b24a4dfa572ce99139
+PKG_SOURCE_DATE:=2021-04-28
+PKG_SOURCE_VERSION:=a63914612904642ed974390fff620f7003ebc20a
+PKG_MIRROR_HASH:=6396a36406ceecf667470d0d673552751573de65497bf97d1e2af3505fe79366
 
 PKG_MAINTAINER:=Daniel Golle <[email protected]>