KVM: arm64: Allow using kvm_nvhe_sym() in hyp code

In order to allow the usage of code shared by the host and the hyp in
static inline library functions, allow the usage of kvm_nvhe_sym() at
EL2 by defaulting to the raw symbol name.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-10-qperret@google.com