MIPS: Move cache sizes to Kconfig

Move details of the L1 cache line sizes & total sizes into Kconfig,
defaulting to 0. A new CONFIG_SYS_CACHE_SIZE_AUTO Kconfig entry is
introduced to allow platforms to select auto-detection of cache sizes,
and it defaults to being enabled if none of the cache sizes are set by
the configuration (ie. sizes are all the default 0), and code is
adjusted to #ifdef on that rather than on the definition of the sizes
(which will always be defined even if 0).

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
diff --git a/arch/mips/lib/cache_init.S b/arch/mips/lib/cache_init.S
index 08b7c3a..4bb9a17 100644
--- a/arch/mips/lib/cache_init.S
+++ b/arch/mips/lib/cache_init.S
@@ -99,14 +99,14 @@
  *
  */
 LEAF(mips_cache_reset)
-#ifdef CONFIG_SYS_ICACHE_SIZE
+#ifndef CONFIG_SYS_CACHE_SIZE_AUTO
 	li	t2, CONFIG_SYS_ICACHE_SIZE
 	li	t8, CONFIG_SYS_CACHELINE_SIZE
 #else
 	l1_info	t2, t8, MIPS_CONF1_IA_SHF
 #endif
 
-#ifdef CONFIG_SYS_DCACHE_SIZE
+#ifndef CONFIG_SYS_CACHE_SIZE_AUTO
 	li	t3, CONFIG_SYS_DCACHE_SIZE
 	li	t9, CONFIG_SYS_CACHELINE_SIZE
 #else
@@ -116,7 +116,7 @@
 #ifdef CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD
 
 	/* Determine the largest L1 cache size */
-#if defined(CONFIG_SYS_ICACHE_SIZE) && defined(CONFIG_SYS_DCACHE_SIZE)
+#ifndef CONFIG_SYS_CACHE_SIZE_AUTO
 #if CONFIG_SYS_ICACHE_SIZE > CONFIG_SYS_DCACHE_SIZE
 	li	v0, CONFIG_SYS_ICACHE_SIZE
 #else