ACPICA: Allow multiple backslash prefix in namepaths

commit d037c5fd7367548191eab2b376a1d08c4ffaf7ff upstream.

In a fully qualified namepath, allow multiple backslash prefixes.
This can happen because of the use of a double-backslash in strings
(since backslash is the escape character) causing confusion.
ACPICA BZ 739 Lin Ming.

http://www.acpica.org/bugzilla/show_bug.cgi?id=739

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Cc: Thomas Renninger <trenn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>