powerpc: C29X: Move CONFIG_PPC_C29X to Kconfig option

Replace CONFIG_PPC_C29X with ARCH_C29X 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 80b3b74..77e3f83 100644
--- a/arch/powerpc/include/asm/config_mpc85xx.h
+++ b/arch/powerpc/include/asm/config_mpc85xx.h
@@ -914,7 +914,7 @@
 #define CONFIG_SYS_FSL_SFP_VER_3_0
 
 
-#elif defined(CONFIG_PPC_C29X)
+#elif defined(CONFIG_ARCH_C29X)
 #define CONFIG_MAX_CPUS			1
 #define CONFIG_FSL_SDHC_V2_3
 #define CONFIG_SYS_FSL_NUM_LAWS		12
@@ -955,7 +955,7 @@
 #define CONFIG_SYS_FSL_DDRC_GEN3
 #endif
 
-#if !defined(CONFIG_PPC_C29X)
+#if !defined(CONFIG_ARCH_C29X)
 #define CONFIG_SYS_FSL_MAX_NUM_OF_SEC	1
 #endif