IB/ipoib: Remove double pointer assigning

There is no need to assign "p" pointer twice.

This patch fixes the following smatch warning:
drivers/infiniband/ulp/ipoib/ipoib_cm.c:517 ipoib_cm_rx_handler() warn:
	missing break? reassigning 'p->id'

Fixes: 839fcaba ("IPoIB: Connected mode experimental support")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>