pine64-pinephone: Fix u-boot user script load address.
Fixes #3414 (closed).
The package device-pine64-pinephone-vccq-mod
installs a u-boot user script.
The user script was loaded at address 0x50700000 partially overwriting
the initramfs (0x4FF00000-0x50883fd1), and causing a boot loop.
The user script load address was increased to 0x50f00000, leaving 16MB of free space for the initramfs, the current initramfs size is 9.52MB.
Tested: Build and install package on Pinephone 1.2a running PMOS 24.12.