OvmfPkg/VirtNorFlashDxe: map flash memory as uncacheable

OvmfPkg/VirtNorFlashDxe: map flash memory as uncacheable

Switching from the ArmPlatformPkg/NorFlashDxe driver to the
OvmfPkg/VirtNorFlashDxe driver had the side effect that flash address
space got registered as EFI_MEMORY_WC instead of EFI_MEMORY_UC.

That confuses the linux kernel's numa code, seems this makes kernel
consider the flash being node memory.  "lsmem" changes from ...

    RANGE                                 SIZE  STATE REMOVABLE BLOCK
    0x0000000040000000-0x000000013fffffff   4G online       yes  8-39

... to ...

    RANGE                                  SIZE  STATE REMOVABLE BLOCK
    0x0000000000000000-0x0000000007ffffff  128M online       yes     0
    0x0000000040000000-0x000000013fffffff    4G online       yes  8-39

... and in the kernel log got new error lines:

    NUMA: Warning: invalid memblk node 512 [mem 0x0000000004000000-0x0000000007ffffff]
    NUMA: Faking a node at [mem 0x0000000004000000-0x000000013fffffff]

Changing the attributes back to EFI_MEMORY_UC fixes this.

Fixes: b92298af8218 ("ArmVirtPkg/ArmVirtQemu: migrate to OVMF's VirtNorFlashDxe")
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>