on gcc's optimization and fails on old gcc. (Tetsuo used gcc 3.3)

We can use __fix_to_vir() instead, because we know it's safe and
don't need link time error reporting.

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Cc: sfr@canb.auug.org.au
LKML-Reference: <49C9FFEA.7060908@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
]n^