RDMA/rxe: Remove redundant page presence check

hmm_pfn_to_page() does not return NULL. ib_umem_odp_map_dma_and_lock()
should return an error in case the target pages cannot be mapped until
timeout, so these checks can safely be removed.

Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Daisuke Matsuda <dskmtsd@gmail.com>
Link: https://patch.msgid.link/20250611162758.10000-1-dskmtsd@gmail.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>