Begin the real driver redesign. For the starters:

- cache the offset of the IDE channel's MISC. control registers which are used
   throughout the driver in hwif->select_data;

- only touch the relevant MCR when detecting the cable type on HPT374's
   function 1;

- make HPT36x's speedproc handler look the same way as HPT37x ones; fix the
   PIO timing register mask for HPT37x.

- rename all the HPT3xx register related variables consistently; clean up the
   whitespace.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>