configs/kontron_bl_imx8mm_defconfig: bump U-boot to 2022.10

Commit 223516b5 (configs/kontron_bl_imx8mm: U-Boot needs util-linux)
added the needed dependency against host-util-linux, but missed an
earlier comment about u-boot still failing [0]

The U-Boot makefile for the host tools does not handle the
compiler/linker options properly. There are some patches [1][2] that fixes
that issue already applied in the newer U-Boot version 2022.10. So we have to
bump U-Boot to fix an autobuilder failure.

Fixes: https://gitlab.com/buildroot.org/buildroot/-/jobs/3267233833

[0] https://lore.kernel.org/buildroot/CAEyMn7Y3UgT-8dYY5rbnzcPfbGmqRVXG=joWx1fSSCC=WiFzbg@mail.gmail.com/


[1] U-Boot: a638bd349ea43825 (kbuild: add KBUILD_HOSTLDFLAGS to cmd_host-csingle)
[2] U-Boot: 31a7688cbe0ed5ed (tools: mkeficapsule: use pkg-config to get -luuid and -lgnutls)

Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
[yann.morin.1998@free.fr:
  - update commit log with reference to [0]
  - slightly tweak commit log
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>