mb/emulation/qemu-i440fx: Tidy up PAM register writes

Tidy up the code that programs the PAM (Programmable Attribute Map)
registers. Introduce the `D0F0_PAM` macro and use it to replace the
magic `0x59` and `0x5a` values in the code. Adjust the range of the
for-loop to work with the `D0F0_PAM` macro, and properly indent the
loop's body.

Change-Id: I9036425d726ffb69737ea6ed36c7a8f61d9d040a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55899
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/mainboard/emulation/qemu-i440fx/mainboard.c b/src/mainboard/emulation/qemu-i440fx/mainboard.c
index bc97554..218c47f 100644
--- a/src/mainboard/emulation/qemu-i440fx/mainboard.c
+++ b/src/mainboard/emulation/qemu-i440fx/mainboard.c
@@ -10,15 +10,15 @@
 	11, 10, 10, 11,
 };
 
+#define D0F0_PAM(x)		(0x59 + (x)) /* 0-6 */
+
 static void qemu_nb_init(struct device *dev)
 {
 	/* Map memory at 0xc0000 - 0xfffff */
 	int i;
-	uint8_t v = pci_read_config8(dev, 0x59);
-	v |= 0x30;
-	pci_write_config8(dev, 0x59, v);
-	for (i = 0; i < 6; i++)
-	pci_write_config8(dev, 0x5a + i, 0x33);
+	pci_or_config8(dev, D0F0_PAM(0), 0x30);
+	for (i = 1; i <= 6; i++)
+		pci_write_config8(dev, D0F0_PAM(i), 0x33);
 
 	/* This sneaked in here, because Qemu does not emulate a SuperIO chip. */
 	pc_keyboard_init(NO_AUX_DEVICE);