target/riscv: Make riscv_cpu_tlb_fill sysemu only

The fallback code in cpu_loop_exit_sigsegv is sufficient
for riscv linux-user.

Remove the code from cpu_loop that raised SIGSEGV.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/riscv/cpu_loop.c

@@ -87,13 +87,6 @@ void cpu_loop(CPURISCVState *env)
             sigcode = TARGET_TRAP_BRKPT;
             sigaddr = env->pc;
             break;
-        case RISCV_EXCP_INST_PAGE_FAULT:
-        case RISCV_EXCP_LOAD_PAGE_FAULT:
-        case RISCV_EXCP_STORE_PAGE_FAULT:
-            signum = TARGET_SIGSEGV;
-            sigcode = TARGET_SEGV_MAPERR;
-            sigaddr = env->badaddr;
-            break;
         case RISCV_EXCP_SEMIHOST:
             env->gpr[xA0] = do_common_semihosting(cs);
             env->pc += 4;