xen/Kconfig: introduce HAS_STATIC_MEMORY

Introduce HAS_STATIC_MEMORY so that STATIC_MEMORY can be enabled or
disabled on a per-architecture basis. ARM selects the new flag; RISC-V
does not, so CONFIG_STATIC_MEMORY is unavailable on RISC-V and
randconfig builds no longer require an explicit STATIC_MEMORY=n override
to avoid a compilation error.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/Kconfig

@@ -21,6 +21,7 @@ config ARM
 	select HAS_DOM0LESS
 	select HAS_GRANT_CACHE_FLUSH if GRANT_TABLE
 	select HAS_STACK_PROTECTOR
+	select HAS_STATIC_MEMORY
 	select HAS_UBSAN
 
 config ARCH_DEFCONFIG

xen/common/Kconfig

@@ -158,6 +158,9 @@ config HAS_PMAP
 config HAS_SCHED_GRANULARITY
 	bool
 
+config HAS_STATIC_MEMORY
+	bool
+
 config HAS_SOFT_RESET
 	bool
 
@@ -193,6 +196,7 @@ config NUMA
 
 config STATIC_MEMORY
 	bool "Static Allocation Support (UNSUPPORTED)" if UNSUPPORTED
+	depends on HAS_STATIC_MEMORY
 	depends on DOM0LESS_BOOT && HAS_DEVICE_TREE_DISCOVERY
 	help
 	  Static Allocation refers to system or sub-system(domains) for