staging: olpc_dcon: Replace a bit shift by a use of BIT.

This patch replaces bit shifting on 1 with the BIT(x) macro
as it's extensively used by other function in the file olpc_dcon.h .

Signed-off-by: Anchal Jain <anchalj109@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>