ARM: OMAP1: fix ams-delta FIQ handler to work with sparse IRQ

After OMAP1 IRQ definitions have been changed by commit 685e2d08


("ARM: OMAP1: Change interrupt numbering for sparse IRQ") introduced
in v4.2, ams-delta FIQ handler which depends on them no longer works
as expected. Fix it.

Created and tested on Amstrad Delta against Linux-4.7-rc3

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>