KVM: selftests: Fix RISC-V compilation

Due to commit 2b7deea3 ("Revert "kvm: selftests: move base
kvm_util.h declarations to kvm_util_base.h"") kvm selftests now
requires explicitly including ucall_common.h when needed. The commit
added the directives everywhere they were needed at the time, but, by
merge time, new places had been merged for RISC-V. Add those now to
fix RISC-V's compilation.

Fixes: dee7ea42

 ("Merge tag 'kvm-x86-selftests_utils-6.10' of https://github.com/kvm-x86/linux into HEAD")
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240603122045.323064-2-ajones@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>