target/xtensa: linux-user: fix fadvise64 call

fadvise64_64 on xtensa passes advice as the second argument and so must
be handled similar to PPC.

This fixes glibc testsuite tests posix/tst-posix_fadvise and
posix/tst-posix_fadvise64.
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>

linux-user/syscall.c

@@ -11509,7 +11509,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
 
 #ifdef TARGET_NR_fadvise64_64
     case TARGET_NR_fadvise64_64:
-#if defined(TARGET_PPC)
+#if defined(TARGET_PPC) || defined(TARGET_XTENSA)
         /* 6 args: fd, advice, offset (high, low), len (high, low) */
         ret = arg2;
         arg2 = arg3;