IB/hfi1: Avoid large frame size warning

When CONFIG_FRAME_WARN is set to 1024 bytes, which is useful to find
stack consumers, we get a warning in hfi1 driver.

drivers/infiniband/hw/hfi1/affinity.c: In function
‘hfi1_get_proc_affinity’:
drivers/infiniband/hw/hfi1/affinity.c:415:1: warning: the frame size of
1056 bytes is larger than 1024 bytes [-Wframe-larger-than=]

This change removes unneeded buf[1024] declaration and usage.

Fixes: f48ad614 ("IB/hfi1: Move driver out of staging")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>