staging: ks7010: use GENMASK instead of custom defines in SME_WEP_VAL_MASK

This commits replaces custom defines that were been used
to define a mask using GENMASK macro from linux bitops
header file.

With this change the "WARNING: line over 80 characters"
warning message reported by checkpatch script is also
removed.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>