staging: vt6655: remove mention of nonexistent function CARDbSetBasicRate

Comments mention a function CARDbSetBasicRate, but it never existed in
the source tree. Remove all mention of it.

Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>