package/freescale-imx/firmware-imx: add options for all i.MX FW needs

package/freescale-imx/firmware-imx: add options for all i.MX FW needs

Some SoCs need a HDMI FW for their bootloader, some other require
EPDC, SDMA and/or VPU.

Instead of trying to "guess" what firmware images need to be installed
in firmware-imx.mk, let the Config framework do the job and allow each
SoC to pick what firmware they need.

Note that this patch should also help introducing an eventual DP FW,
as Gary mentioned in a separate thread [1].

[1] http://lists.busybox.net/pipermail/buildroot/2020-May/283181.html

Suggested-by: Yann E. MORIN <yann.morin.1998@free.fr>
Suggested-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Stephane Viau <stephane.viau@oss.nxp.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>