staging/omapdrm: Fix spacing coding style in omap_plane.c

The following errors and warnings fixed.
- ERROR: code indent should use tabs where possible
- WARNING: please, no spaces at the start of a line

Signed-off-by: YAMANE Toshiaki <yamanetoshi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>