powerpc/85xx: Fix compile errors if CONFIG_SYS_{BR,OR}0_PRELIM aren't set

Add ifdef protection in LBC code to handle the case in which
CONFIG_SYS_BR0_PRELIM and CONFIG_SYS_OR0_PRELIM arent defined for a
build.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

arch/powerpc/cpu/mpc8xxx/fsl_lbc.c

@@ -58,8 +58,10 @@ void init_early_memctl_regs(void)
 #endif
 	/* now restrict to preliminary range */
 	if (init_br1) {
+#if defined(CONFIG_SYS_BR0_PRELIM) && defined(CONFIG_SYS_OR0_PRELIM)
 		set_lbc_br(0, CONFIG_SYS_BR0_PRELIM);
 		set_lbc_or(0, CONFIG_SYS_OR0_PRELIM);
+#endif
 
 #if defined(CONFIG_SYS_BR1_PRELIM) && defined(CONFIG_SYS_OR1_PRELIM)
 		set_lbc_or(1, CONFIG_SYS_OR1_PRELIM);