x86/pci: Remove unused variable

|arch/x86/pci/ce4100.c: In function `ce4100_conf_read':
|arch/x86/pci/ce4100.c:257:9: warning: unused variable `retval'

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: dirk.brandewie@gmail.com
LKML-Reference: <1292600033-12271-16-git-send-email-bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>