[SRU] Building ubuntu-cpc,icicle fails on Jammy

[Heinrich Schuchardt]

Raising the image size from 4.5 to 6 GiB resolves the issue.

[ Impact ]

https://launchpad.net/~ubuntu-cdimage/+livefs/ubuntu/jammy/cpc/+build/672072 shows a build failure

update-initramfs: Generating /boot/initrd.img-6.8.0-41-generic
cpio: write error: No space left on device
E: mkinitramfs failure cpio 2
update-initramfs: failed for /boot/initrd.img-6.8.0-41-generic with 1.

[ Test Plan ]

Build images with

ARCH=riscv64 SUBARCH='icicle' PROJECT=ubuntu-cpc IMAGEFORMAT=ext4 SUITE=jammy

ARCH=riscv64 SUBARCH='generic' PROJECT=ubuntu-cpc IMAGEFORMAT=ext4 SUITE=jammy

Boot the images on the Microchip Icicle Kit and QEMU respectively. For details see

https://wiki.ubuntu.com/RISC-V/QEMU and
https://wiki.ubuntu.com/RISC-V/PolarFire%20SoC%20FPGA%20Icicle%20Kit

[ Where problems could occur ]

Only RISC-V builds are concerned.

Building might fail due to the increased image size.

The built images might not be bootable.

[ Other Info ]

n/a

[Heinrich Schuchardt (xypron)]

https://code.launchpad.net/~xypron/livecd-rootfs/+git/livecd-rootfs/+merge/471702