PowerPC: Update MIP405/MIP405T to use Kconfig better

Convert CONFIG_MIP405T from SYS_EXTRA_OPTIONS to a real config

There are two boards, MIP405 and MIP405T that have a few differences.
Start by checking for CONFIG_TARGET_MIP405.  Then introduce
CONFIG_TARGET_MIP405T and use that not CONFIG_MIP405T.  Next, convert
also convert the usage of CONFIG_ISO_STRING to be based on Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/mpl/common/pci_parts.h b/board/mpl/common/pci_parts.h
index 4193e92..75e8cae 100644
--- a/board/mpl/common/pci_parts.h
+++ b/board/mpl/common/pci_parts.h
@@ -91,7 +91,7 @@
 static struct pci_pip405_config_entry piix4_ide_cntrl_f1[] = {
 	{PCI_CFG_PIIX4_BMIBA,	0x0001000,	4}, /* set BMI to a valid address */
 	{PCI_COMMAND,		0x0001,		2}, /* enable IO access	*/
-#if !defined(CONFIG_MIP405T)
+#if !defined(CONFIG_TARGET_MIP405T)
 	{PCI_CFG_PIIX4_IDETIM,	0x80008000,	4}, /* enable Both IDE channels	*/
 #else
 	{PCI_CFG_PIIX4_IDETIM,	0x00008000,	4}, /* enable IDE channel0	*/
@@ -101,7 +101,7 @@
 
 /* PIIX4 USB Controller Function 2 */
 static struct pci_pip405_config_entry piix4_usb_cntrl_f2[] = {
-#if !defined(CONFIG_MIP405T)
+#if !defined(CONFIG_TARGET_MIP405T)
 	{PCI_INTERRUPT_LINE,	31,		1}, /* Int vector = 31		*/
 	{PCI_BASE_ADDRESS_4,	0x0000E001,	4}, /* Set IO Address to 0xe000 to 0xe01F */
 	{PCI_LATENCY_TIMER,	0x80,		1}, /* Latency Timer 0x80	*/