This patch fixes sparse warning for static declaration of variable "use_dma"

drivers/mtd/nand/omap2.c:114:11: warning: symbol 'use_dma' was not declared. Should it be static?
Signed-off-by: NG, Manjunath Kondaiah <manjugk@ti.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>