efi: Enable EFI_SET_VIRTUAL_ADDRESS_MAP by default

Many machines fails to boot if this option is disabled.
It's off by default as it was deemed too risky for being enabled
by default late in the Xen 4.13 cycle, but found out to be safe.
As there are no known drawback by having this option on, enable
it by default.

Signed-off-by: Teddy Astie <teddy.astie@vates.tech>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

xen/common/Kconfig

@@ -363,14 +363,13 @@ config KEXEC
 
 config EFI_SET_VIRTUAL_ADDRESS_MAP
     bool "EFI: call SetVirtualAddressMap()" if EXPERT
+    default y
     help
       Call EFI SetVirtualAddressMap() runtime service to setup memory map for
       further runtime services. According to UEFI spec, it isn't strictly
       necessary, but many UEFI implementations misbehave when this call is
       missing.
 
-      If unsure, say N.
-
 config XSM
 	bool "Xen Security Modules support"
 	default ARM