arm64: kernel/sys.c - silence initialization warnings.

[Valdis Klētnieks]

Building arch/arm64/kernel/sys.o with W=1 throws over 300 warnings:

/usr/src/linux-next/arch/arm64/kernel/sys.c:56:40: warning: initialized field overwritten [-Woverride-init]
   56 | #define __SYSCALL(nr, sym)      [nr] = __arm64_##sym,
      |                                        ^~~~~~~~
/usr/src/linux-next/include/uapi/asm-generic/unistd.h:29:37: note: in expansion of macro '__SYSCALL'
   29 | #define __SC_COMP(_nr, _sys, _comp) __SYSCALL(_nr, _sys)
      |                                     ^~~~~~~~~
/usr/src/linux-next/include/uapi/asm-generic/unistd.h:34:1: note: in expansion of macro '__SC_COMP'
   34 | __SC_COMP(__NR_io_setup, sys_io_setup, compat_sys_io_setup)
      | ^~~~~~~~~

We know that's pretty much the file's purpose in life, so tell the
build system to not remind us.  This makes the 1 other warning a
lot more noticeable. 

Signed-off-by: Valdis Kletnieks <valdis.kletnieks at vt.edu>

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index ed65576ce710..916b21d2b35b 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -8,6 +8,7 @@ CFLAGS_armv8_deprecated.o := -I$(src)
 CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_insn.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_return_address.o = $(CC_FLAGS_FTRACE)
+CFLAGS_sys.o += $(call cc-disable-warning, override-init)
 
 # Object file lists.
 obj-y			:= debug-monitors.o entry.o irq.o fpsimd.o		\