pata-rb532-cf: drop custom freeze and thaw

I'm not quite sure what freezing and thawing is used for. Tests showed
that the port is being frozen at initialisation state and thawed right
afterwards, then the functions were not called anymore. Dropping the
complete custom code for handling the frozen state seems to work at
least for a standard use case including mounting a partition, copying
some files in it (in parallel) and finally removing them and unmounting
the partition.

Signed-off-by: Phil Sutter <n0-1@freewrt.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>