debug: coredump: flash partition: Use K_NO_WAIT when in ISR

This code is meant to run in the context of a exception.
Most architectures will fail the asertion made in z_impl_k_sem_take()
when timeout is not K_NO_WAIT.

This commit ensures K_NO_WAIT is used when arch_is_in_isr() is true.

Signed-off-by: Lucas Tamborrino <lucas.tamborrino@espressif.com>