vme_tsi148: Fix typo in tsi148_slave_get()

This patch corrects a typo where "vme_base" was used instead of
"*vme_base". The typo resulted in an incorrect value being returned
to userspace (via vme_user).

It also removes the following compile warning on some platforms:

warning: cast from pointer to integer of different size

[asierra: commit title/log rewording]
Signed-off-by: Joe Schultz <jschultz@xes-inc.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>