RDMA/rxe: Fix mismatched max_msg_sz

User mode queries max_msg_sz as 0x800000 by command 'ibv_devinfo -v',
however ibv_post_send/ibv_post_recv has a limit of 2^31. Fix this
mismatched information.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Fixes: f605f26e ("RDMA/rxe: Protect QP state with qp->state_lock")
Fixes: 5bf944f2 ("RDMA/rxe: Add error messages")
Link: https://patch.msgid.link/20241216121953.765331-1-pizhenwei@bytedance.com


Review-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>