powerpc: MPC8568: Remove macro CONFIG_MPC8568

Replace CONFIG_MPC8568 with ARCH_MPC8568 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 ef591b9..c38d983 100644
--- a/arch/powerpc/include/asm/config_mpc85xx.h
+++ b/arch/powerpc/include/asm/config_mpc85xx.h
@@ -98,7 +98,7 @@
 #define CONFIG_SYS_FSL_DDRC_GEN1
 #define CONFIG_SYS_CCSRBAR_DEFAULT	0xff700000
 
-#elif defined(CONFIG_MPC8568)
+#elif defined(CONFIG_ARCH_MPC8568)
 #define CONFIG_MAX_CPUS			1
 #define CONFIG_SYS_FSL_NUM_LAWS		10
 #define CONFIG_SYS_FSL_DDRC_GEN2
diff --git a/arch/powerpc/include/asm/immap_85xx.h b/arch/powerpc/include/asm/immap_85xx.h
index d6e7f62..ec4c837 100644
--- a/arch/powerpc/include/asm/immap_85xx.h
+++ b/arch/powerpc/include/asm/immap_85xx.h
@@ -2484,7 +2484,7 @@
 	u32	svr;		/* System version */
 	u8	res10[8];
 	u32	rstcr;		/* Reset control */
-#if defined(CONFIG_MPC8568)||defined(CONFIG_MPC8569)
+#if defined(CONFIG_ARCH_MPC8568) || defined(CONFIG_MPC8569)
 	u8	res11a[76];
 	par_io_t qe_par_io[7];
 	u8	res11b[1600];