Staging: gdm724x: Simplify the struct gdm_endian to a variable.

Since the testing for host endianness and in-driver conversion were
removed in 77e8a501, the gdm_endian struct contains only one member,
and can therefore be simplified to a single u8 variable.

Signed-off-by: Quytelda Kahja <quytelda@tamalin.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>