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/arch/powerpc/include/asm/config_mpc85xx.h b/arch/powerpc/include/asm/config_mpc85xx.h
index dc8a696..cd47883 100644
--- a/arch/powerpc/include/asm/config_mpc85xx.h
+++ b/arch/powerpc/include/asm/config_mpc85xx.h
@@ -300,7 +300,7 @@
 #define CONFIG_SYS_FSL_ERRATUM_A004477
 #define CONFIG_USB_MAX_CONTROLLER_COUNT	1
 
-#elif defined(CONFIG_PPC_P2041) /* also supports P2040 */
+#elif defined(CONFIG_ARCH_P2041) /* also supports P2040 */
 #define CONFIG_SYS_FSL_QORIQ_CHASSIS1
 #define CONFIG_FSL_CORENET		/* Freescale CoreNet platform */
 #define CONFIG_MAX_CPUS			4