x86/build: Silence the build with "make -s"

x86/build: Silence the build with "make -s"

Every kernel build on x86 will result in some output:

  Setup is 13084 bytes (padded to 13312 bytes).
  System is 4833 kB
  CRC 6d35fa35
  Kernel: arch/x86/boot/bzImage is ready  (#2)

This shuts it up, so that 'make -s' is truely silent as long as
everything works. Building without '-s' should produce unchanged
output.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170719125310.2487451-6-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>