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: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 924fd68..5ef5176 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -11509,7 +11509,7 @@
 
 #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;