package/freescale-imx/firmware-imx: add choice for DDR training binaries

package/freescale-imx/firmware-imx: add choice for DDR training binaries

Several i.MX8 (e.g.: 8M, 8MM, 8MN) support many DDR types (LPDDR4, DDR4,
etc.), for which the DDR training is performed in the bootloader.
Some boards have LPDDR4 (e.g.: nitrogen8mn) and some others have the DDR4
(e.g.: NXP's reference board EVK). This patch allows the selection of either
of the binaries used to train the DDR.

Note that DDR and HDMI FW copies are now separated, which makes latter
being properly copied only for the relevant SoC (i.MX8MQ).
Suggested-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Stephane Viau <stephane.viau@oss.nxp.com>
Reviewed-by: Maeva Manuel <maeva.manuel@oss.nxp.com>
Reviewed-by: Julien Olivain <julien.olivain@oss.nxp.com>
Reviewed-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>