powerpc/eeh: Fix use-after-release of EEH driver

Correct two cases where eeh_pcid_get() is used to reference the driver's
module but the reference is dropped before the driver pointer is used.

In eeh_rmv_device() also refactor a little so that only two calls to
eeh_pcid_put() are needed, rather than three and the reference isn't
taken at all if it wasn't needed.

Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>