This parameter is needed by the PCI driver-mode interface but is always
NULL on x86. There are a number of calls to this function so it makes
sense to minimise the parameters.

Adjust the x86 function to omit the first parameter, and introduce stub
functions to handle the conversion.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: rebase the patch against u-boot-x86/next to get it applied cleanly]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>