configs: khadas-vim3*_android: fix AVB oom error

When booting Android with AVB enabled, an OOM is observed:

  => avb init ${mmcdev}
  => avb verify _a
  ## Android Verified Boot 2.0 version 1.1.0
  read_is_device_unlocked not supported yet
  read_rollback_index not supported yet
  avb_util.c:182: ERROR: Failed to allocate memory.
  OOM error occurred during verification

A custom malloc length of 128MB is required as documented in
commit 285a83b1 ("configs: meson64_android: increase SYS_MALLOC_LEN to 128M for AVB")

However, this 128M custom malloc length was not ported to Kconfig in
commit 7cfbba36 ("Convert CONFIG_SYS_MALLOC_LEN to Kconfig")

Add it back to fix AVB verification on VIM3/VIM3L.

Fixes: 7cfbba36 ("Convert CONFIG_SYS_MALLOC_LEN to Kconfig")
Co-developed-by: Guillaume La Roque <glaroque@baylibre.com>
Signed-off-by: Guillaume La Roque <glaroque@baylibre.com>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Link: https://lore.kernel.org/r/20240209-vim3-avb-malloc-v1-1-91427d8c19ab@baylibre.com


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>