x86: array can become static

In arch/x86/kernel/setup_64.c, the standard_io_resources array
is needlessly defined as global. This patch makes this variable
static.

This patch was successfully build-tested using the defconfig
for x86_64. Runtime test was performed by booting a 64-bit x86
box up to the shell prompt.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>