ppc4xx: Complete remove bogus dflush()

Since the current dflush() implementation is know to have some problems
(as seem on lwmon5 ECC init) this patch removes it completely and replaces
it by using clean_dcache_range().

Tested on Katmai with ECC DIMM.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/cpu/ppc4xx/denali_spd_ddr2.c b/cpu/ppc4xx/denali_spd_ddr2.c
index e20c9eb..acf0f49 100644
--- a/cpu/ppc4xx/denali_spd_ddr2.c
+++ b/cpu/ppc4xx/denali_spd_ddr2.c
@@ -92,7 +92,6 @@
 extern int denali_wait_for_dlllock(void);
 extern void denali_core_search_data_eye(void);
 extern void dcbz_area(u32 start_address, u32 num_bytes);
-extern void dflush(void);
 
 /*
  * Board-specific Platform code can reimplement spd_ddr_init_hang () if needed
@@ -1201,7 +1200,8 @@
 #else
 #error Please define CFG_MEM_TOP_HIDE (see README) in your board config file
 #endif
-	dflush();
+	/* Write modified dcache lines back to memory */
+	clean_dcache_range(CFG_SDRAM_BASE, CFG_SDRAM_BASE + dram_size - CFG_MEM_TOP_HIDE);
 	debug("Completed\n");
 	sync();
 	remove_tlb(CFG_SDRAM_BASE, dram_size);