davinci: DM365: fix duplicate default IRQ priorities

IRQ 29 has two possible interrupts DDRINT and RTC, but having both in
the default priority table is confusing (and triggers a warning from
sparse.)

This patch removes the lower priority DDRINT from the default priority
table leaving the RTC setting as the default.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>