hikey: Add HIKEY_USE_LEGACY_TI_BLUETOOTH build option to transition to common bluetooth HAL

This patch, a reworked version of changes from Satish Patel
adds a build option to enable the common generic linux bluetooth
HAL vs the legacy TI HAL.

The legacy TI HAL is only needed on 4.4 and older kernels.

NOTE: One needs to be using a kernel that supports the standard
linux hci0 interface to successfully use this.

Change-Id: I74927aa651b184fdb65957fcb54c4c0afffbfa7c
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/hikey.mk b/hikey.mk
index 3174ba4..779ee87 100644
--- a/hikey.mk
+++ b/hikey.mk
@@ -3,10 +3,17 @@
 endif
 TARGET_PREBUILT_KERNEL := device/linaro/hikey-kernel/Image-dtb-$(TARGET_KERNEL_USE)
 TARGET_PREBUILT_DTB := device/linaro/hikey-kernel/hi6220-hikey.dtb-$(TARGET_KERNEL_USE)
+
 ifeq ($(TARGET_KERNEL_USE), 3.18)
-TARGET_FSTAB := fstab.hikey-$(TARGET_KERNEL_USE)
+  TARGET_FSTAB := fstab.hikey-$(TARGET_KERNEL_USE)
+  HIKEY_USE_LEGACY_TI_BLUETOOTH := true
 else
-TARGET_FSTAB := fstab.hikey
+  ifeq ($(TARGET_KERNEL_USE), 4.4)
+    HIKEY_USE_LEGACY_TI_BLUETOOTH := true
+  else
+    HIKEY_USE_LEGACY_TI_BLUETOOTH := false
+  endif
+  TARGET_FSTAB := fstab.hikey
 endif
 
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