ntb_hw_switchtec: potential shift wrapping bug in switchtec_ntb_init_sndev()

This code triggers a Smatch warning:

    drivers/ntb/hw/mscc/ntb_hw_switchtec.c:884 switchtec_ntb_init_sndev()
    warn: should '(1 << sndev->peer_partition)' be a 64 bit type?

The "part_map" and "tpart_vec" variables are u64 type so this seems like
a valid warning.

Fixes: 3df54c87 ("ntb_hw_switchtec: Allow using Switchtec NTB in multi-partition setups")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>