at91: Minor tweaks to SPL logic for space savings on smartweb

- spl_board_init is empty on smartweb so drop that function
- When CONFIG_AT91SAM9_WATCHDOG is set we do not disable the watchdog in
  SPL and instead let full U-Boot handle it.  Instead of an empty
  function just do not call a function.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3e05f79..d273294 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -393,7 +393,7 @@
 
 config ARCH_AT91
 	bool "Atmel AT91"
-	select SPL_BOARD_INIT if SPL
+	select SPL_BOARD_INIT if SPL && !TARGET_SMARTWEB
 
 config TARGET_EDB93XX
 	bool "Support edb93xx"