target/riscv/kvm: remove sneaky strerrorname_np() instance

Commit d424db2 excluded some strerrorname_np() instances because they
break musl libc builds. Another instance happened to slip by via commit
d4ff3da.

Remove it before it causes trouble again.

Fixes: d4ff3da (target/riscv/kvm: initialize 'vlenb' via get-reg-list)
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/riscv/kvm/kvm-cpu.c

@@ -1054,8 +1054,8 @@ static void kvm_riscv_read_vlenb(RISCVCPU *cpu, KVMScratchCPU *kvmcpu,
 
         ret = ioctl(kvmcpu->cpufd, KVM_GET_ONE_REG, &reg);
         if (ret != 0) {
-            error_report("Unable to read vlenb register, error code: %s",
-                         strerrorname_np(errno));
+            error_report("Unable to read vlenb register, error code: %d",
+                         errno);
             exit(EXIT_FAILURE);
         }