kernel: updated default IDLE_STACK_SIZE to 512 for RISCV32

Default 256 bytes stack size for idle task is not enough, as
stack grows/shrinks by a multiple of 16-bytes in the
RISC-V architecture.

Increase it to 512 bytes for RISCV32 architecture

Change-Id: I8321c48e4c1a877b252ba5561f3cbdd1fe475fc7
Signed-off-by: Jean-Paul Etienne <fractalclone@gmail.com>
1 file changed