ARC: Cleanup old Kconfig IO scheduler options

CONFIG_IOSCHED_DEADLINE and CONFIG_IOSCHED_CFQ are gone since
commit f382fb0b

 ("block: remove legacy IO schedulers").

The IOSCHED_DEADLINE was replaced by MQ_IOSCHED_DEADLINE and it will be
now enabled by default (along with MQ_IOSCHED_KYBER).

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>