USB: ohci-omap - avoid including mach/irqs.h

ohci-omap doesn't need to include mach/irqs.h - nothing within this
driver needs anything from this header file.  Remove this include.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>