arm/mpu: Kconfig symbols for MPU build

The MPU system requires static memory to work, select that
when building this memory management subsystem.

While there, provide a restriction for the ARM_EFI Kconfig
parameter to be built only when !MPU, the EFI stub is not
used as there are no implementation of UEFI services for
armv8-r.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/Kconfig

@@ -85,6 +85,7 @@ config MMU
 
 config MPU
 	bool "MPU" if UNSUPPORTED
+	select STATIC_MEMORY
 	help
 	  Memory Protection Unit (MPU). Select if you plan to run Xen on ARMv8-R
 	  systems supporting EL2. (UNSUPPORTED)
@@ -102,7 +103,7 @@ config ACPI
 
 config ARM_EFI
 	bool "UEFI boot service support"
-	depends on ARM_64
+	depends on ARM_64 && !MPU
 	default y
 	help
 	  This option provides support for boot services through