linux-wandboard

linux/dma-mapping.h: rename macro to prevent multiple inclusion

Having the macro to prevent multiple inclusion of
include/linux/dma-mapping.h contain the prefix "_ASM" is just begging
for possible confusion some day.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>