This patch fixes the MISRA-C violations in arch/x86/io.c.
* make the function have only one exit point
v1 -> v2:
* replace `ASSERT` with `pr_err`
Tracked-On: #861
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>