USB: New functions to check endpoints info.

These functions makes USB driver's code simpler when dealing with endpoints
by avoiding them from accessing the endpoint's descriptor structure directly
when they only need to know the endpoint's transfer type and/or
direction.

Please, read each functions' documentation in order to know how to use
them.

Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>