qcom_utils: Only define QCOM_BOARD_PLATFORMS if compiling kernel inline

	* If using prebuilt kernel KERNEL_OBJ/usr will not exist, thus
	  build will complain of dir missing during module compilation

	** Requires TARGET_USE_PREBUILT_KERNEL := true in BoardConfig for now

Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>
Change-Id: Iecd8c97e89504c60d2f01926318468ac7eb396f9