at86rf230: Add macro for TRX STATE MASK
at86rf230: Add macro for TRX STATE MASK

Instead of using the 'magic' number of 0x1f the TRX_STATE_MASK macro is
introduced.

Signed-off-by: Christoffer Holmstedt <57b2abdf2f241b4c2d424ff7e3849e115eb19fdf@gmail.com>
Signed-off-by: Alexander Aring <d03dbcdedb9639e397df9b8578e8fc8274f4e6c4@gmail.com>
Signed-off-by: Marcel Holtmann <44592b4eea36663c86b994bb0ea99d15309c1c7d@holtmann.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs