MKALL-barebox.sh: add fake firmware/imx8mp-bl31.bin

We need firmware/imx8mp-bl31.bin after the commit

  > commit 3c0d42752e9aa0cee0c6f33f237cf0409de529a7
  > Author: Oleksij Rempel <[email protected]>
  > Date:   Tue Jun 2 14:07:02 2020 +0200
  >
  >     arm: imx: add initial imx8mp support

Signed-off-by: Antony Pavlov <[email protected]>

Author: frantony

MKALL-barebox.sh

@@ -21,6 +21,7 @@ touch arch/arm/boards/plathome-openblocks-ax3/binary.0
 touch arch/arm/boards/turris-omnia/binary.0
 touch firmware/fsl_fman_ucode_ls1046_r1.0_106_4_18.bin
 touch firmware/imx8mm-bl31.bin
+touch firmware/imx8mp-bl31.bin
 touch firmware/imx8mq-bl31.bin
 touch firmware/lpddr4_pmu_train_1d_dmem.bin
 touch firmware/lpddr4_pmu_train_1d_imem.bin