powerpc: MPC8555: Remove macro CONFIG_MPC8555

Replace CONFIG_MPC8555 with ARCH_MPC8555 in Kconfig and clean up existing
macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/include/asm/cpm_85xx.h b/arch/powerpc/include/asm/cpm_85xx.h
index e89e2f0..b46e20e 100644
--- a/arch/powerpc/include/asm/cpm_85xx.h
+++ b/arch/powerpc/include/asm/cpm_85xx.h
@@ -77,7 +77,7 @@
  */
 #define CPM_DATAONLY_BASE	((uint)128)
 #define CPM_DP_NOSPACE		((uint)0x7FFFFFFF)
-#if defined(CONFIG_ARCH_MPC8541) || defined(CONFIG_MPC8555)
+#if defined(CONFIG_ARCH_MPC8541) || defined(CONFIG_ARCH_MPC8555)
 #define CPM_FCC_SPECIAL_BASE	((uint)0x00009000)
 #define CPM_DATAONLY_SIZE	((uint)(8 * 1024) - CPM_DATAONLY_BASE)
 #else	/* MPC8540, MPC8560 */