kbuild: Fix missing system calls check on mips.

Commit 5f7efb4 (Kbuild: append missing-syscalls to the default target
list) broke MIPS build.

Reported-tested-and-acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/Kbuild b/Kbuild
index 4caab4f..b8b708a 100644
--- a/Kbuild
+++ b/Kbuild
@@ -92,7 +92,7 @@
 targets += missing-syscalls
 
 quiet_cmd_syscalls = CALL    $<
-      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)
+      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
 
 missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
 	$(call cmd,syscalls)