configs/ti_am62ax_sk_defconfig: switch to am62x op-tee platform flavor

Since optee_os bump to 4.5.0 in commit [1], the ti_am62ax_sk_defconfig
fails to build with error:

    core/arch/arm/plat-k3/drivers/sa2ul.c:36:42: error: 'SA2UL_BASE' undeclared here (not in a function); did you mean 'SCU_BASE'?
       36 | register_phys_mem_pgdir(MEM_AREA_IO_SEC, SA2UL_BASE, SA2UL_REG_SIZE);
          |                                          ^~~~~~~~~~

This is due to a logic change in platform flavor selection in upstream.
See [2].

There is unfortunately no SA2UL_BASE defined for the am62ax in op-tee
which is causing the op-tee builds to fail however the platform is
identical to the am62x platform. So for now let's switch to using the
am62x which has the proper configuration for this SoC even if it's
mislabeled.

Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/9690372425

[1] https://gitlab.com/buildroot.org/buildroot/-/commit/14ef1ed7d27ba2f6d99bbdd0d80f67df50fccce9
[2] https://github.com/OP-TEE/optee_os/commit/35c75f355c98242290e342c04648e91baf35a4f3

Signed-off-by: Bryan Brattlof <bb@ti.com>
[Julien: add extra info in commit log]
Signed-off-by: Julien Olivain <ju.o@free.fr>

configs/ti_am62ax_sk_defconfig

@@ -23,7 +23,7 @@ BR2_TARGET_ARM_TRUSTED_FIRMWARE_PLATFORM="k3"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_TARGET_BOARD="lite"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_BL32_OPTEE=y
 BR2_TARGET_OPTEE_OS=y
-BR2_TARGET_OPTEE_OS_PLATFORM="k3-am62ax"
+BR2_TARGET_OPTEE_OS_PLATFORM="k3-am62x"
 BR2_TARGET_TI_K3_R5_LOADER=y
 BR2_TARGET_TI_K3_R5_LOADER_CUSTOM_VERSION=y
 BR2_TARGET_TI_K3_R5_LOADER_CUSTOM_VERSION_VALUE="2024.07"