pine64-pinephonepro: remove u-boot-pine64-pinephonepro dependency (MR 3049)

We're using Tow-Boot now, so remove this as it is unnecessary and
makes the package unbuildable since the dependency doesn't exist
any more.

Fixes d26cc84c32

Closes https://gitlab.com/postmarketOS/pmaports/-/issues/1483

device/testing/device-pine64-pinephonepro/APKBUILD

@@ -3,7 +3,7 @@
 pkgname=device-pine64-pinephonepro
 pkgdesc="PINE64 PinePhone Pro"
 pkgver=2.0
-pkgrel=0
+pkgrel=1
 url="https://postmarketos.org"
 license="MIT"
 arch="aarch64"
@@ -16,7 +16,6 @@ depends="
 	linux-pine64-pinephonepro
 	mesa-dri-gallium
 	postmarketos-base
-	u-boot-pine64-pinephonepro
 	fwupd
 	fwupd-plugin-modem_manager
 	fwupd-plugin-fastboot