powerpc: P2041: Remove macro CONFIG_PPC_P2041

Replace CONFIG_PPC_P2041 with ARCH_P2041 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 a4c0ea0..9e8c420 100644
--- a/drivers/net/fm/Makefile
+++ b/drivers/net/fm/Makefile
@@ -19,7 +19,7 @@
 # SoC specific SERDES support
 obj-$(CONFIG_ARCH_P1023)	+= p1023.o
 # The P204x, P304x, and P5020 are the same
-obj-$(CONFIG_PPC_P2041) += p5020.o
+obj-$(CONFIG_ARCH_P2041) += p5020.o
 obj-$(CONFIG_PPC_P3041) += p5020.o
 obj-$(CONFIG_PPC_P4080) += p4080.o
 obj-$(CONFIG_PPC_P5020) += p5020.o