tuna: Set TARGET_BOOTLOADER_TYPE=fastboot

Set TARGET_BOOTLOADER_TYPE=fastboot so we can start using
ifeq ($(TARGET_BOOTLOADER_TYPE),fastboot)
to detect devices using fastboot --
ifeq ($(TARGET_BOOTLOADER_TYPE),uboot)
would break compatibility with our ICS builds (where uboot
is always the thing to use and TARGET_BOOTLOADER_TYPE is never
defined)

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
diff --git a/BoardConfig.mk b/BoardConfig.mk
index 1b4a332..b0db389 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -94,3 +94,5 @@
 BOARD_SEPOLICY_UNION := \
         genfs_contexts \
         file_contexts
+
+TARGET_BOOTLOADER_TYPE := fastboot