iwlegacy: use IS_ENABLED() instead of checking for built-in or module

The IS_ENABLED() macro checks if a Kconfig symbol has been enabled either
built-in or as a module, use that macro instead of open coding the same.

Using the macro makes the code more readable by helping abstract away some
of the Kconfig built-in and module enable details.
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/wireless/intel/iwlegacy/common.h

@@ -1320,7 +1320,7 @@ struct il_priv {
 	u64 timestamp;
 
 	union {
-#if defined(CONFIG_IWL3945) || defined(CONFIG_IWL3945_MODULE)
+#if IS_ENABLED(CONFIG_IWL3945)
 		struct {
 			void *shared_virt;
 			dma_addr_t shared_phys;
@@ -1351,7 +1351,7 @@ struct il_priv {
 
 		} _3945;
 #endif
-#if defined(CONFIG_IWL4965) || defined(CONFIG_IWL4965_MODULE)
+#if IS_ENABLED(CONFIG_IWL4965)
 		struct {
 			struct il_rx_phy_res last_phy_res;
 			bool last_phy_res_valid;