smc911x: Fix undefined CONFIG_ symbol warning

elif defined(CONFIG_*) should be used instead of elif CONFIG_*
so GCC doesn't give warnings about undefined symbols when the config
option is disabled.

Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/smc911x.h

@@ -37,7 +37,7 @@
   #define SMC_USE_16BIT		0
   #define SMC_USE_32BIT		1
   #define SMC_IRQ_SENSE		IRQF_TRIGGER_FALLING
-#elif CONFIG_SH_MAGIC_PANEL_R2
+#elif defined(CONFIG_SH_MAGIC_PANEL_R2)
   #define SMC_USE_SH_DMA	0
   #define SMC_USE_16BIT		0
   #define SMC_USE_32BIT		1