powerpc: T1040: Remove macro CONFIG_PPC_T1040

Replace CONFIG_PPC_T1040 with ARCH_T1040 in Kconfig and clean up
existing macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/cpu/mpc85xx/fdt.c b/arch/powerpc/cpu/mpc85xx/fdt.c
index eeee92c..aaca15f 100644
--- a/arch/powerpc/cpu/mpc85xx/fdt.c
+++ b/arch/powerpc/cpu/mpc85xx/fdt.c
@@ -556,7 +556,7 @@
 #define fdt_fixup_dma3(x)
 #endif
 
-#if defined(CONFIG_PPC_T1040)
+#if defined(CONFIG_ARCH_T1040)
 static void fdt_fixup_l2_switch(void *blob)
 {
 	uchar l2swaddr[6];