csky: Cleanup old Kconfig options

CONFIG_CLKSRC_OF is gone since commit bb0eb050
("clocksource/drivers: Rename CLKSRC_OF to TIMER_OF").  The platform
already selects TIMER_OF.

CONFIG_HAVE_DMA_API_DEBUG is gone since commit 6e88628d ("dma-debug:
remove CONFIG_HAVE_DMA_API_DEBUG").

CONFIG_DEFAULT_DEADLINE is gone since commit f382fb0b

 ("block:
remove legacy IO schedulers").

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>