UBUNTU: SAUCE: Make CONFIG_DRM_HISI_HIBMC depend on ARM64

UBUNTU: SAUCE: Make CONFIG_DRM_HISI_HIBMC depend on ARM64

BugLink: https://bugs.launchpad.net/bugs/1762940
Hisilicon developed hibmc_drm for their arm64 based soc and did not
intend for this driver to be used on any other architecture than arm64.

Using it on amd64 leads to the screen being unreadable, forcing users to
manually blacklist the module on the kernel command line to use the d-i
server installer.

Make CONFIG_DRM_HISI_HIBMC firmly depend on arm64 to ensure it is not
built for other architectures.

Signed-off-by: Matthew Ruffell <matthew.ruffell@canonical.com>
Acked-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>