drivers: dma: smartbond: Fix power policy handling

Function dma_smartbond_set_channel_status() used incorrect
condition to release state lock.
In initialization function dma_smartbond_init() function
dma_smartbond_set_channel_status() was called for each DMA
channel and tried to release lock that was never taken.

Signed-off-by: Jerzy Kasenberg <jerzy.kasenberg@codecoup.pl>