target-arm/arm-semi.c: Fix broken SYS_WRITE0 via gdb

A spurious trailing "\n" in the gdb syscall format string used
for SYS_WRITE0 meant that gdb would reject the remote syscall,
with the effect that the output from the guest was silently dropped.
Remove the newline so that gdb accepts the packet.

Cc: qemu-stable@nongnu.org
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
(cherry picked from commit 857b55ad)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

target-arm/arm-semi.c

@@ -260,7 +260,7 @@ uint32_t do_arm_semihosting(CPUARMState *env)
             return (uint32_t)-1;
         len = strlen(s);
         if (use_gdb_syscalls()) {
-            gdb_do_syscall(arm_semi_cb, "write,2,%x,%x\n", args, len);
+            gdb_do_syscall(arm_semi_cb, "write,2,%x,%x", args, len);
             ret = env->regs[0];
         } else {
             ret = write(STDERR_FILENO, s, len);