omap: remove obsolete kernel version support

target/linux/omap/config-3.18

target/linux/omap/config-4.1

.../patches-3.18/0334-video-da8xx-fb-adding-dt-support.patch

...ideo-da8xx-fb-Add-API-to-register-wait-for-vsync-ca.patch

...ideo-da8xx-fb-fix-defect-with-vsync-callback-invoca.patch

.../920-arm-dts-am335x-evmsk-add-support-for-lcd-panel.patch

...linux/omap/patches-3.18/950-am335x-evmsk-wilink-dts.patch

...p/patches-4.1/0334-video-da8xx-fb-adding-dt-support.patch

...ideo-da8xx-fb-Add-API-to-register-wait-for-vsync-ca.patch

...ideo-da8xx-fb-fix-defect-with-vsync-callback-invoca.patch

.../920-arm-dts-am335x-evmsk-add-support-for-lcd-panel.patch

.../linux/omap/patches-4.1/950-am335x-evmsk-wilink-dts.patch