configs: reduce stack size of Sipeed MAIX

The K210 has only 8 MiB RAM thereof 2 MiB reserved for AI.

Allow only 1 MiB for the stack.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/configs/sipeed_maix_bitm_defconfig b/configs/sipeed_maix_bitm_defconfig
index 96651f0..459bf0d 100644
--- a/configs/sipeed_maix_bitm_defconfig
+++ b/configs/sipeed_maix_bitm_defconfig
@@ -1,6 +1,7 @@
 CONFIG_RISCV=y
 CONFIG_TARGET_SIPEED_MAIX=y
 CONFIG_ARCH_RV64I=y
+CONFIG_STACK_SIZE=0x100000
 # CONFIG_NET is not set
 # CONFIG_INPUT is not set
 # CONFIG_DM_ETH is not set