hikey: Remove TARGET_COMPRESSED_KERNEL build option

At this point, the hikey UEFI bootlaoder supports Image.gz, so
it should be fine to drop support for the old uncompressed
Image-dtb

Change-Id: I837596e44c00c5cc8af4909d56ac550595dd1017
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/hikey-common.mk b/hikey-common.mk
index 86909f1..ce10c89 100644
--- a/hikey-common.mk
+++ b/hikey-common.mk
@@ -3,17 +3,9 @@
 TARGET_KERNEL_USE=4.9
 endif
 
-ifndef TARGET_COMPRESSED_KERNEL
-TARGET_COMPRESSED_KERNEL=true
-endif
-
 HIKEY_USE_DRM_HWCOMPOSER := false
 
-ifeq ($(TARGET_COMPRESSED_KERNEL), false)
-TARGET_PREBUILT_KERNEL := device/linaro/hikey-kernel/Image-dtb-$(TARGET_KERNEL_USE)
-else
 TARGET_PREBUILT_KERNEL := device/linaro/hikey-kernel/Image.gz-dtb-$(TARGET_KERNEL_USE)
-endif
 
 TARGET_PREBUILT_DTB := device/linaro/hikey-kernel/hi6220-hikey.dtb-$(TARGET_KERNEL_USE)