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/fsl_lbc.h b/arch/powerpc/include/asm/fsl_lbc.h
index c7805e9..ff9b2d9 100644
--- a/arch/powerpc/include/asm/fsl_lbc.h
+++ b/arch/powerpc/include/asm/fsl_lbc.h
@@ -326,7 +326,7 @@
 #define LCRR_CLKDIV			0x0000001F
 #define LCRR_CLKDIV_SHIFT		0
 #if defined(CONFIG_MPC83xx) || defined(CONFIG_ARCH_MPC8540) || \
-	defined(CONFIG_ARCH_MPC8541) || defined(CONFIG_MPC8555) || \
+	defined(CONFIG_ARCH_MPC8541) || defined(CONFIG_ARCH_MPC8555) || \
 	defined(CONFIG_MPC8560)
 #define LCRR_CLKDIV_2			0x00000002
 #define LCRR_CLKDIV_4			0x00000004