KVM: arm64: Fix missing <asm/stackpage/nvhe.h> include

Include <asm/stackpage/nvhe.h> for kvm_arm_hyp_stack_base
declaration which fixes the following sparse warning:

arch/arm64/kvm/arm.c:63:1: warning: symbol 'kvm_arm_hyp_stack_base' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Link: https://patch.msgid.link/20260112160413.603493-1-ben.dooks@codethink.co.uk
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: bjdooks-ct

arch/arm64/kvm/arm.c

@@ -40,6 +40,7 @@
 #include <asm/kvm_pkvm.h>
 #include <asm/kvm_ptrauth.h>
 #include <asm/sections.h>
+#include <asm/stacktrace/nvhe.h>
 
 #include <kvm/arm_hypercalls.h>
 #include <kvm/arm_pmu.h>