irq-renesas-irqc: simplify irq_set_type() method

Value 0 of the sense  selection field of CONFIG_n register means "disable event
detection" and serves in irqc_sense[] for marking the invalid values of the IRQ
type (by just omitting initializers). There is no need for INTC_IRQ_SENSE_VALID
and hence INTC_IRQ_SENSE() as all field values matching to the  valid IRQ types
are non-zero anyway.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>