staging: vt6655: [BUG] Protect MACvSelectPage1 with lock.

The device must not flip to page 1 while in interrupt lock causing
loss of connection or dead lock.

Protect from changes to page by adding lock where user can
change the page in CARDvSetRSPINF, vnt_configure and set_channel

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>