gma500: Convert spaces to tabs in accel_2d.c.

Convert the spaces within the accel_2d.c file to tabs in order to comply
with the coding style of the kernel.
Signed-off-by: Akshay Joshi <me@akshayjoshi.com>
[Trimmed to subset relevant to current tree]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>