KVM: arm64: tracing: add ftrace dependency

Selecting CONFIG_TRACE_REMOTE causes a build time warning when FTRACE
is disabled:

WARNING: unmet direct dependencies detected for TRACE_REMOTE
Depends on [n]: FTRACE [=n]
Selected by [y]:
- NVHE_EL2_TRACING [=y] && VIRTUALIZATION [=y] && KVM [=y] && NVHE_EL2_DEBUG [=y] && TRACING [=y]

Add this as another dependency to ensure a clean build.

Fixes: 3aed038aac8d ("KVM: arm64: Add trace remote for the nVHE/pKVM hyp")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Link: https://patch.msgid.link/20260312123601.625063-3-arnd@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>