Get rid of the nonsense in the CONFIG_CPU_HAS_PREFETCH block.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1327,8 +1327,7 @@ config SIBYTE_DMA_PAGEOPS
 	  SiByte Linux port.  Seems to give a small performance benefit.
 
 config CPU_HAS_PREFETCH
-	bool "Enable prefetches" if CPU_SB1 && !CPU_SB1_PASS_2
-	default y if CPU_MIPS32 || CPU_MIPS64 || CPU_RM7000 || CPU_RM9000 || CPU_R10000
+	bool
 
 config MIPS_MT
 	bool "Enable MIPS MT"