src: Never set ISA Enable on PCI bridges

Looks like no one really knows what this bit would be useful for, nor
when it would need to be set. Especially if coreboot is setting it even
on PCI *Express* bridges. Digging through git history, nearly all
instances of setting it on PCIe bridges comes from i82801gx, for which
no reason was given as to why this would be needed. The other instances
in Intel code seem to have been, unsurprisingly, copy-pasted.

Drop all uses of this definition and rename it to avoid confusion. The
negation in the name could trick people into setting this bit again.

Tested on Asrock B85M Pro4, no visible difference.

Change-Id: Ifaff29561769c111fb7897e95dbea842faec5df4
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43775
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
diff --git a/src/soc/intel/common/block/pcie/pcie.c b/src/soc/intel/common/block/pcie/pcie.c
index f36366a..ada380e 100644
--- a/src/soc/intel/common/block/pcie/pcie.c
+++ b/src/soc/intel/common/block/pcie/pcie.c
@@ -24,9 +24,8 @@
 	/* Set Cache Line Size to 0x10 */
 	pci_write_config8(dev, PCI_CACHE_LINE_SIZE, CACHE_LINE_SIZE);
 
-	/* disable parity error response, enable ISA */
-	pci_update_config16(dev, PCI_BRIDGE_CONTROL,
-			    ~PCI_BRIDGE_CTL_PARITY, PCI_BRIDGE_CTL_NO_ISA);
+	/* disable parity error response */
+	pci_and_config16(dev, PCI_BRIDGE_CONTROL, ~PCI_BRIDGE_CTL_PARITY);
 
 	if (CONFIG(PCIE_DEBUG_INFO)) {
 		printk(BIOS_SPEW, "    MBL    = 0x%08x\n",