ppc: Remove MPC8315ERDB board

This board has not been converted to CONFIG_DM_PCI by the deadline and is
also missing conversion to CONFIG_DM.  Remove it.  As this is the last
ARCH_MPC8315 platform, remove that support as well.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/powerpc/include/asm/arch-mpc83xx/gpio.h b/arch/powerpc/include/asm/arch-mpc83xx/gpio.h
index 8a6896e..b740675 100644
--- a/arch/powerpc/include/asm/arch-mpc83xx/gpio.h
+++ b/arch/powerpc/include/asm/arch-mpc83xx/gpio.h
@@ -6,8 +6,7 @@
 /*
  * The MCP83xx's 1-2 GPIO controllers each with 32 bits.
  */
-#if defined(CONFIG_ARCH_MPC8313) || defined(CONFIG_ARCH_MPC8308) || \
-	defined(CONFIG_ARCH_MPC8315)
+#if defined(CONFIG_ARCH_MPC8313) || defined(CONFIG_ARCH_MPC8308)
 #define MPC83XX_GPIO_CTRLRS 1
 #elif defined(CONFIG_ARCH_MPC834X) || defined(CONFIG_ARCH_MPC837X) || \
 	defined(CONFIG_ARCH_MPC8309)