accel/kvm: Remove kvm_init_cpu_signals() stub

Since commit 57038a92bb ("cpus: extract out kvm-specific code
to accel/kvm") the kvm_init_cpu_signals() stub is not necessary.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Message-Id: <20250703173248.44995-6-philmd@linaro.org>

accel/stubs/kvm-stub.c

@@ -105,11 +105,6 @@ unsigned int kvm_get_free_memslots(void)
     return 0;
 }
 
-void kvm_init_cpu_signals(CPUState *cpu)
-{
-    abort();
-}
-
 bool kvm_arm_supports_user_irq(void)
 {
     return false;