powerpc: MPC8641: Remove macro CONFIG_MPC8641

Replace CONFIG_MPC8641 with ARCH_MPC8641 in Kconfig and clean up
existing macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/include/asm/config_mpc86xx.h b/arch/powerpc/include/asm/config_mpc86xx.h
index 96340af..e3d94e3 100644
--- a/arch/powerpc/include/asm/config_mpc86xx.h
+++ b/arch/powerpc/include/asm/config_mpc86xx.h
@@ -15,7 +15,7 @@
 #define CONFIG_MAX_CPUS			1
 #define CONFIG_SYS_FSL_NUM_LAWS		10
 
-#elif defined(CONFIG_MPC8641)
+#elif defined(CONFIG_ARCH_MPC8641)
 #define CONFIG_MAX_CPUS			2
 #define CONFIG_SYS_FSL_NUM_LAWS		10
 
diff --git a/arch/powerpc/include/asm/fsl_law.h b/arch/powerpc/include/asm/fsl_law.h
index eee78c8..b348cc1 100644
--- a/arch/powerpc/include/asm/fsl_law.h
+++ b/arch/powerpc/include/asm/fsl_law.h
@@ -79,7 +79,7 @@
 enum law_trgt_if {
 	LAW_TRGT_IF_PCI = 0x00,
 	LAW_TRGT_IF_PCI_2 = 0x01,
-#ifndef CONFIG_MPC8641
+#ifndef CONFIG_ARCH_MPC8641
 	LAW_TRGT_IF_PCIE_1 = 0x02,
 #endif
 #if defined(CONFIG_ARCH_BSC9131) || defined(CONFIG_ARCH_BSC9132)
@@ -117,7 +117,7 @@
 #define LAW_TRGT_IF_RIO_1	LAW_TRGT_IF_RIO
 #define LAW_TRGT_IF_IFC		LAW_TRGT_IF_LBC
 
-#ifdef CONFIG_MPC8641
+#ifdef CONFIG_ARCH_MPC8641
 #define LAW_TRGT_IF_PCIE_1	LAW_TRGT_IF_PCI
 #endif