[qca-ssdk] update kernel version to 3.18.21

linux has been updated from 3.18.19 to 3.18.21, so ssdk
driver config needs to updated with kernel version 3.18.21
This change will fix compilation problem in date.

Change-Id: I75e9d5ea5cf81cab65fa8f70283e05c94ba8eadf
Signed-off-by: Ram Chandra Jangir <rjangi@codeaurora.org>
diff --git a/config b/config
index 4f6650c..6dcabbc 100755
--- a/config
+++ b/config
@@ -14,7 +14,7 @@
 OS_VER=3_18
 endif
 
-ifeq ($(KVER), 3.18.19)
+ifeq ($(KVER), 3.18.21)
 OS_VER=3_18
 endif
 
@@ -86,7 +86,7 @@
 ifeq ($(KVER), 3.4.103)
   CPU_CFLAG=-D__LINUX_ARM_ARCH__=7  -DMODULE -fno-common -DCONFIG_MMU -D$(BOARD_NAME)
 endif
-ifeq ($(KVER), 3.18.19)
+ifeq ($(KVER), 3.18.21)
   CPU_CFLAG=-D__LINUX_ARM_ARCH__=7  -DMODULE -fno-common -DCONFIG_MMU -D$(BOARD_NAME)
 endif