target/nios2: Remove user-only nios2_cpu_do_interrupt

Since 7827168, this function is unused for user-only,
when the TCGCPUOps.do_interrupt hook itself became system-only.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220421151735.31996-10-richard.henderson@linaro.org>

target/nios2/helper.c

@@ -30,14 +30,6 @@
 
 #if defined(CONFIG_USER_ONLY)
 
-void nios2_cpu_do_interrupt(CPUState *cs)
-{
-    Nios2CPU *cpu = NIOS2_CPU(cs);
-    CPUNios2State *env = &cpu->env;
-    cs->exception_index = -1;
-    env->regs[R_EA] = env->regs[R_PC] + 4;
-}
-
 void nios2_cpu_record_sigsegv(CPUState *cs, vaddr addr,
                               MMUAccessType access_type,
                               bool maperr, uintptr_t retaddr)