display: Fix handling of QCOM_BSP

 * Only set this CFLAG if the device declares TARGET_USES_QCOM_BSP.

Change-Id: Id1c02c5d1cca9016d46005333ba1e2a22e75e1cb
Don't build when variant is requested.

Change-Id: I32adc414e5e68af6c409115583984a09d65b6587