MIPS: c-r4k: Drop bc_wback_inv() from icache flush

The EVA conditional bc_wback_inv() at the end of flush_icache_range() to
flush the modified code all the way back to RAM was apparently there for
debug purposes and to accommodate the Malta EVA configuration which
makes use of a physical alias, and didn't use the CP0_EBase.WG (Write
Gate) bit to put the exception vector in the same physical alias where
the exception vector code is written and is being flushed.

Now that CP0_EBase.WG is used, lets drop this flush.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14151/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/c-r4k.c

@@ -752,17 +752,6 @@ static inline void __local_r4k_flush_icache_range(unsigned long start,
 			break;
 		}
 	}
-#ifdef CONFIG_EVA
-	/*
-	 * Due to all possible segment mappings, there might cache aliases
-	 * caused by the bootloader being in non-EVA mode, and the CPU switching
-	 * to EVA during early kernel init. It's best to flush the scache
-	 * to avoid having secondary cores fetching stale data and lead to
-	 * kernel crashes.
-	 */
-	bc_wback_inv(start, (end - start));
-	__sync();
-#endif
 }
 
 static inline void local_r4k_flush_icache_range(unsigned long start,