powerpc: P4080: Remove macro CONFIG_PPC_P4080

Replace CONFIG_PPC_P4080 with ARCH_P4080 in Kconfig and clean up
existing macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/drivers/net/fm/Makefile b/drivers/net/fm/Makefile
index b435ecd..46dc6df 100644
--- a/drivers/net/fm/Makefile
+++ b/drivers/net/fm/Makefile
@@ -21,7 +21,7 @@
 # The P204x, P304x, and P5020 are the same
 obj-$(CONFIG_ARCH_P2041) += p5020.o
 obj-$(CONFIG_ARCH_P3041) += p5020.o
-obj-$(CONFIG_PPC_P4080) += p4080.o
+obj-$(CONFIG_ARCH_P4080) += p4080.o
 obj-$(CONFIG_PPC_P5020) += p5020.o
 obj-$(CONFIG_PPC_P5040) += p5040.o
 obj-$(CONFIG_PPC_T1040) += t1040.o