powerpc: P5040: Remove macro CONFIG_P5040

Replace CONFIG_P5040 with ARCH_P5040 in Kconfig and clean up
existing macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/board/varisys/cyrus/eth.c b/board/varisys/cyrus/eth.c
index bcadc67..fc2192a 100644
--- a/board/varisys/cyrus/eth.c
+++ b/board/varisys/cyrus/eth.c
@@ -19,7 +19,7 @@
 #define FIRST_PORT_ADDR 3
 #define SECOND_PORT_ADDR 7
 
-#ifdef CONFIG_PPC_P5040
+#ifdef CONFIG_ARCH_P5040
 #define FIRST_PORT FM1_DTSEC5
 #define SECOND_PORT FM2_DTSEC5
 #else
@@ -83,7 +83,7 @@
 			fm_disable_port(i);
 	}
 
-#ifdef CONFIG_PPC_P5040
+#ifdef CONFIG_ARCH_P5040
 	for (i = FM2_DTSEC2; i < FM2_DTSEC1 + CONFIG_SYS_NUM_FM2_DTSEC; i++) {
 		if (!IS_VALID_PORT(i))
 			fm_disable_port(i);