misc: remove GENWQE_DEBUGFS_RO()

We already have the DEFINE_SHOW_ATTRIBUTE.There is no need to define
such a macro,so remove GENWQE_DEBUGFS_RO.Also use DEFINE_SHOW_ATTRIBUTE
to simplify some code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>