Bugfix/cva6 support (#447)

This Pull request is to fix wrong platform.h path for cva6 target and
also align 32 and 64 bit buildroot configuration

overlays/keystone/configs/riscv32_cva6_defconfig

@@ -12,6 +12,7 @@ BR2_GLOBAL_PATCH_DIR="$(BR2_EXTERNAL_KEYSTONE_PATH)/patches $(BR2_EXTERNAL_KEYST
 BR2_PER_PACKAGE_DIRECTORIES=y
 BR2_SSP_NONE=y
 BR2_TARGET_GENERIC_ROOT_PASSWD="sifive"
+BR2_SYSTEM_BIN_SH_BASH=y
 BR2_SYSTEM_DHCP="eth0"
 BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_KEYSTONE_PATH)/board/cva6/post-build.sh"
 BR2_LINUX_KERNEL=y

sm/src/objects.mk

@@ -15,7 +15,12 @@ keystone-sm-headers += crypto.h ed25519/ed25519.h ed25519/fe.h ed25519/fixedint.
 endif
 
 # Platform headers
-keystone-sm-headers += platform/$(KEYSTONE_PLATFORM)/platform.h
+ifeq ($(KEYSTONE_PLATFORM),cva6)
+    #for CVA6, the actual target platform is fpga/ariane, so PLATFORM variable is used
+    keystone-sm-headers += platform/$(PLATFORM)/platform.h
+else
+    keystone-sm-headers += platform/$(KEYSTONE_PLATFORM)/platform.h
+endif
 
 ifeq ($(KEYSTONE_PLATFORM),sifive/fu540)
 	keystone-sm-headers += platform/sifive/fu540/waymasks.h