wlan: Update SMD and SMSM header includes (revised)

Commit "wlan: Update SMD and SMSM header includes" added a mechanism
to determine which SMD and SMSM include files are present in the
kernel.  This change utilized modifications to both Android.mk and
Kbuild to make this determination.  This works fine when the wlan
driver is being built as part of an Android build (and hence
Android.mk and Kbuild are both used), but this does not work when the
wlan driver is being built as part of a kernel build (and hence Kbuild
alone is used), such as with Nexus products.  Remove the logic that
was added to Android.mk, and instead add equivalent logic to Kbuild.

Change-Id: Iee7ccf64b74401db52947cc4099678fdcb46f9f6
CRs-fixed: 595745
diff --git a/Kbuild b/Kbuild
index 749a6e8..113e831 100644
--- a/Kbuild
+++ b/Kbuild
@@ -645,11 +645,14 @@
 
 CDEFINES += -DFEATURE_WLAN_CH_AVOID
 
-ifeq ($(EXISTS_MSM_SMD),1)
+# Some kernel include files are being moved.  Check to see if
+# the old version of the files are present
+
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/mach-msm/include/mach/msm_smd.h),)
 CDEFINES += -DEXISTS_MSM_SMD
 endif
 
-ifeq ($(EXISTS_MSM_SMSM),1)
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/mach-msm/include/mach/msm_smsm.h),)
 CDEFINES += -DEXISTS_MSM_SMSM
 endif