Move dram_init_banksize() to a common header

This is an weak function present on all archs so we should have it in the
common header file. Remove it from arch-specific headers and add a
function comment.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/arm/include/asm/u-boot-arm.h

@@ -36,7 +36,6 @@ int	arch_early_init_r(void);
 
 /* board/.../... */
 int	board_init(void);
-int dram_init_banksize(void);
 void	board_quiesce_devices(void);
 
 /* cpu/.../interrupt.c */

arch/x86/include/asm/u-boot-x86.h

@@ -41,7 +41,6 @@ void x86_disable_caches(void);
 int x86_init_cache(void);
 void reset_cpu(ulong addr);
 ulong board_get_usable_ram_top(ulong total_size);
-int dram_init_banksize(void);
 int default_print_cpuinfo(void);
 
 /* Set up a UART which can be used with printch(), printhex8(), etc. */

include/common.h

@@ -203,6 +203,23 @@ typedef void (interrupt_handler_t)(void *);
  */
 int dram_init(void);
 
+/**
+ * dram_init_banksize() - Set up DRAM bank sizes
+ *
+ * This can be implemented by boards to set up the DRAM bank information in
+ * gd->bd->bi_dram(). It is called just before relocation, after dram_init()
+ * is called.
+ *
+ * If this is not provided, a default implementation will try to set up a
+ * single bank. It will do this if CONFIG_NR_DRAM_BANKS and
+ * CONFIG_SYS_SDRAM_BASE are set. The bank will have a start address of
+ * CONFIG_SYS_SDRAM_BASE and the size will be determined by a call to
+ * get_effective_memsize().
+ *
+ * @return 0 if OK, -ve on error
+ */
+int dram_init_banksize(void);
+
 void	hang		(void) __attribute__ ((noreturn));
 
 int	timer_init(void);