iwlwifi: fix modular 3945 only build

If only 3945 is selected, and is a module, build
fails because iwl-legacy.c won't be compiled. Fix
this by adding it to the build correctly.

This doesn't happen for 4965 because it is a bool
option, not tristate, since it's built into the
AGN module.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/Makefile

@@ -7,6 +7,10 @@ iwlcore-$(CONFIG_IWL4965) += iwl-legacy.o
 iwlcore-$(CONFIG_IWLWIFI_DEBUGFS) += iwl-debugfs.o
 iwlcore-$(CONFIG_IWLWIFI_DEVICE_TRACING) += iwl-devtrace.o
 
+# If 3945 is selected only, iwl-legacy.o will be added
+# to iwlcore-m above, but it needs to be built in.
+iwlcore-objs += $(iwlcore-m)
+
 CFLAGS_iwl-devtrace.o := -I$(src)
 
 # AGN