ARM: omap: remove references to disable_irq_lch

The disable_irq_lch method is never actually used, so there's not much
point it existing; remove it.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --cc arch/arm/mach-omap1/dma.c
Simple merge

diff --cc arch/arm/mach-omap2/dma.c
Simple merge

diff --cc include/linux/omap-dma.h
Simple merge