console: Use explicit pointer type for vc_uni_pagedir* fields

The vc_data.vc_uni_pagedir filed is currently long int, supposedly to
be served generically.  This, however, leads to lots of cast to
pointer, and rather it worsens the readability significantly.

Actually, we have now only a single uni_pagedir map implementation,
and this won't change likely.  So, it'd be much more simple and
error-prone to just use the exact pointer for struct uni_pagedir
instead of long.

Ditto for vc_uni_pagedir_loc.  It's a pointer to the uni_pagedir, thus
it can be changed similarly to the exact type.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>