powerpc: B4420: Remove macro CONFIG_PPC_B4420

Replace CONFIG_PPC_B4420 with ARCH_B4420 in Kconfig and clean up
existing macros.
diff --git a/board/freescale/b4860qds/b4860qds.c b/board/freescale/b4860qds/b4860qds.c
index c2ceb80..83a7015 100644
--- a/board/freescale/b4860qds/b4860qds.c
+++ b/board/freescale/b4860qds/b4860qds.c
@@ -437,7 +437,7 @@
 		}
 		break;
 
-#ifdef CONFIG_PPC_B4420
+#ifdef CONFIG_ARCH_B4420
 	case 0x17:
 	case 0x18:
 			/*
@@ -496,7 +496,7 @@
 	/* Configure VSC3308 crossbar switch */
 	ret = select_i2c_ch_pca(I2C_CH_VSC3308);
 	switch (serdes2_prtcl) {
-#ifdef CONFIG_PPC_B4420
+#ifdef CONFIG_ARCH_B4420
 	case 0x9d:
 #endif
 	case 0x9E:
@@ -929,7 +929,7 @@
 	 * For this SerDes2's Refclk1 need to be set to 100MHz
 	 */
 	switch (serdes2_prtcl) {
-#ifdef CONFIG_PPC_B4420
+#ifdef CONFIG_ARCH_B4420
 	case 0x9d:
 #endif
 	case 0x9E:
diff --git a/board/freescale/b4860qds/b4860qds_crossbar_con.h b/board/freescale/b4860qds/b4860qds_crossbar_con.h
index fcccb8f..901f8b0 100644
--- a/board/freescale/b4860qds/b4860qds_crossbar_con.h
+++ b/board/freescale/b4860qds/b4860qds_crossbar_con.h
@@ -28,7 +28,7 @@
 				{7, 8}, {9, 0}, {5, 14},
 				{4, 15}, {2, 12}, {12, 13} };
 
-#ifdef CONFIG_PPC_B4420
+#ifdef CONFIG_ARCH_B4420
 static int8_t vsc16_tx_sgmii_lane_cd[8][2] = { {5, 14}, {4, 15},
 		{-1, -1}, {-1, -1}, {-1, -1}, {-1, -1}, {-1, -1}, {-1, -1} };
 #endif
@@ -54,7 +54,7 @@
 				{7, 8}, {1, 9}, {14, 11},
 				{15, 10}, {13, 3}, {12, 12} };
 
-#ifdef CONFIG_PPC_B4420
+#ifdef CONFIG_ARCH_B4420
 static int8_t vsc16_rx_sgmii_lane_cd[8][2] = { {14, 11}, {15, 10},
 		{-1, -1}, {-1, -1}, {-1, -1}, {-1, -1}, {-1, -1}, {-1, -1} };
 #endif
diff --git a/board/freescale/b4860qds/eth_b4860qds.c b/board/freescale/b4860qds/eth_b4860qds.c
index 164ec0a..89a1883 100644
--- a/board/freescale/b4860qds/eth_b4860qds.c
+++ b/board/freescale/b4860qds/eth_b4860qds.c
@@ -213,7 +213,7 @@
 		fm_info_set_phy_address(FM1_DTSEC6,
 				CONFIG_SYS_FM1_ONBOARD_PHY2_ADDR);
 		break;
-#ifdef CONFIG_PPC_B4420
+#ifdef CONFIG_ARCH_B4420
 	case 0x17:
 	case 0x18:
 		/* Serdes 1: A-D SGMII, Configuring on board dual SGMII Phy */