xen/arm: hvm_domain does not need to be cacheline aligned

hvm_domain only contains the HVM_PARAM that on ARM are not used often.
So it is not necessary to have hvm_domain fitting in a cacheline. Drop
it to save 128 bytes in the structure arch_domain.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/include/asm-arm/domain.h

@@ -14,7 +14,7 @@
 struct hvm_domain
 {
     uint64_t              params[HVM_NR_PARAMS];
-}  __cacheline_aligned;
+};
 
 #ifdef CONFIG_ARM_64
 enum domain_type {