x86/platform/uv: Remove existing /sys/firmware/sgi_uv/ interface

Remove existing interface at /sys/firmware/sgi_uv/, created by
arch/x86/platform/uv/uv_sysfs.c

This interface includes:
/sys/firmware/sgi_uv/coherence_id
/sys/firmware/sgi_uv/partition_id

Both coherence_id and partition_id will be re-introduced via a
new uv_sysfs driver.

Signed-off-by: Justin Ernst <justin.ernst@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lkml.kernel.org/r/20201125175444.279074-2-justin.ernst@hpe.com