arm: qemu: disable the EFI workaround for older GRUB

The QEMU/mach-virt targeted port of u-boot currently only runs on
QEMU under TCG emulation, which does not model the caches at all,
and so no users can exist that are relying on the GRUB hack for
EFI boot.

We will shortly enable support for running under KVM, but the GRUB
hack (which disables all caches without doing cache cleaning by VA
during ExitBootServices()) is likely to cause more problems than it
solves, given that KVM hosts require correct maintenance if they
incorporate non-architected system caches.

So let's disable the GRUB hack by default on the QEMU/mach-virt
port.

Signed-off-by: Ard Biesheuvel <[email protected]>
Reviewed-by: Heinrich Schuchardt <[email protected]>

Author: ardbiesheuvel

configs/qemu_arm_defconfig

@@ -47,3 +47,4 @@ CONFIG_USB=y
 CONFIG_DM_USB=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_EHCI_PCI=y
+# CONFIG_EFI_GRUB_ARM32_WORKAROUND is not set